Initial access for PRACH transmissions

Abstract

A wireless transmit receive unit (WTRU) may receive an indication of a transmitted synchronization signal block (SSB) included in a SSB burst and an indication of a skipped SSB in the SSB burst. The skipped SSB is not transmitted by the base station in the SSB burst. The WTRU may determine to send an indication that the WTRU wants to use the skipped SSB for or after the initial access procedure. The WTRU may transmit a random access preamble using a random access resource and receive at least one downlink transmission using a beam associated with the skipped SSB.

Description

[0001] Cross-references to related applications This application claims the benefit of U.S. Provisional Patent Application No. 63 / 457,029, filed April 4, 2023, the entire contents of which are incorporated herein by reference. Background Technology

[0002] NR, or New Radio, is a 5G mobile communication standard developed by the 3rd Generation Partnership Project (3GPP) to provide high-speed and reliable wireless communication services. NR includes a variety of features and technologies to improve communication quality, increase network capacity, and reduce latency. Beam selection is one of the key features of NR, contributing to improved wireless communication performance. Beam selection involves selecting the optimal beam direction, or beamforming, for transmitting and receiving wireless signals. By using beamforming, NR can focus transmitted energy in a specific direction, which can improve signal quality, reduce interference, and increase network range and capacity. Summary of the Invention

[0003] A wireless transmit / receive unit (WTRU) can receive, within a synchronization signal block (SSB) burst, an indication of a set of one or more transmitted SSBs and an indication of a set of one or more skipped SSBs. Each of the one or more skipped SSBs may not be transmitted by a base station within the SSB burst. The WTRU can determine and transmit an indication of a first skipped SSB among the one or more skipped SSBs. The WTRU may use one or more random access resources to transmit a random access preamble. The random access preamble, or one or more of the one or more random access resources, may indicate the first skipped SSB. The WTRU may use a beam associated with the first skipped SSB to receive at least one downlink transmission.

[0004] The WTRU can also receive configuration information associated with the one or more transmitted SSBs. The configuration information may include a candidate beam list. The candidate beam list may include beams associated with the first skipped SSB.

[0005] In one embodiment, the configuration information may include a beam index, azimuth, elevation, or aiming angle. The random access preamble may be transmitted using a beam associated with a first transmitted SSB in a set of one or more transmitted SSBs, and the random access preamble associated with the first transmitted SSB or one or more random access resources may indicate the first skipped SSB.

[0006] In one example, the one or more random access resources may include a first random access resource and a second random access resource. The first random access resource may be associated with a first transmitted SSB, and the second random access resource may be associated with a first skipped SSB.

[0007] The WTRU can be further configured to receive an indication of whether the SSB skip configuration is enabled.

[0008] The WTRU can also be configured to use an artificial intelligence (AI) / machine learning (ML) model to predict a preferred list of SSBs from a set of one or more skipped SSBs. The one or more random access resources can be based on the one or more transmitted SSBs, the one or more skipped SSBs, or a combination of the one or more transmitted SSBs and the one or more skipped SSBs.

[0009] In one example, the first skipped SSB of the one or more skipped SSBs may be used during the initial access procedure or after the initial access procedure. An indication sent in the random access message 3 using the one or more random access resources may indicate the first skipped SSB. Attached Figure Description

[0010] Figure 1A This is a system diagram illustrating an example communication system in which one or more of the disclosed embodiments may be implemented.

[0011] Figure 1B The illustration shows a device that can be used according to one embodiment. Figure 1A The diagram shows a system diagram of an example wireless transmit / receive unit (WTRU) used in a communication system.

[0012] Figure 1C The illustration shows a device that can be used according to one embodiment. Figure 1A The diagram shows a system diagram of an example radio access network (RAN) and an example core network (CN) used in a communication system.

[0013] Figure 1D The illustration shows a device that can be used according to one embodiment. Figure 1A The diagram shows a system diagram of a further example RAN and a further example CN used within the communication system.

[0014] Figure 2 This is a diagram illustrating an example of firing a subset of the SSB that is skipped. Detailed Implementation

[0015] Figure 1AThis diagram illustrates an example communication system 100 in which one or more of the disclosed embodiments may be implemented. The communication system 100 may be a multiple access system that provides content (such as voice, data, video, messaging, broadcasting, etc.) to multiple wireless users. The communication system 100 enables multiple wireless users to access such content by sharing system resources (including wireless bandwidth). For example, the communication system 100 may employ one or more channel access methods, such as Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal FDMA (OFDMA), Single Carrier FDMA (SC-FDMA), Zero-Tail Unique Word DFT Extended OFDM (ZT UW DTS-s OFDM), Unique Word OFDM (UW-OFDM), Resource Block Filtered OFDM, Filter Bank Multicarrier (FBMC), etc.

[0016] like Figure 1A As shown, the communication system 100 may include wireless transmit / receive units (WTRUs) 102a, 102b, 102c, 102d, RAN 104 / 113, CN 106 / 115, Public Switched Telephone Network (PSTN) 108, Internet 110, and other networks 112. Although it will be appreciated, the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and / or network elements. Each of the WTRUs 102a, 102b, 102c, and 102d can be any type of device configured to operate and / or communicate in a wireless environment. As examples, WTRUs 102a, 102b, 102c, and 102d (any of which may be referred to as a “station” and / or “STA”) may be configured to transmit and / or receive wireless signals and may include user equipment (UE), mobile stations, fixed or mobile subscriber units, subscription-based units, pagers, cellular phones, personal digital assistants (PDAs), smartphones, laptops, netbooks, personal computers, wireless sensors, hotspots or Mi-Fi devices, Internet of Things (IoT) devices, watches or other wearable devices, head-mounted displays (HMDs), vehicles, drones, medical devices and applications (e.g., remote surgery), industrial devices and applications (e.g., robots and / or other wireless devices operating in industrial and / or automated processing chain scenarios), consumer electronics devices, devices operating on commercial and / or industrial wireless networks, etc. Any of WTRUs 102a, 102b, 102c, and 102d may be interchangeably referred to as WTRUs. Furthermore, any description of the UEs described herein may be equivalently applied to WTRUs (or vice versa). For example, the WTRU can be configured to execute any of the procedures or programs described herein as being executed by the UE (or vice versa).

[0017] The communication system 100 may also include base station 114a and / or base station 114b. Each of base stations 114a and 114b may be any type of device configured to wirelessly interface with at least one of WTRUs 102a, 102b, 102c, and 102d to facilitate access to one or more communication networks, such as CN 106 / 115, the Internet 110, and / or other networks 112. As an example, base stations 114a and 114b may be any of a base transceiver station (BTS), Node-B, eNode B, home node B, home eNode B, gNB, NR NodeB, site controller, access point (AP), wireless router, etc. Although base stations 114a and 114b are depicted as single elements, it will be understood that base stations 114a and 114b may include any number of interconnected base stations and / or network elements.

[0018] Base station 114a may be part of RAN 104 / 113, which may also include other base stations and / or network elements (not shown), such as base station controllers (BSCs), radio network controllers (RNCs), relay nodes, etc. Base station 114a and / or base station 114b may be configured to transmit and / or receive radio signals on one or more carrier frequencies, which may be referred to as cells (not shown). These frequencies may be licensed spectrum, unlicensed spectrum, or a combination of licensed and unlicensed spectrum. A cell may provide coverage for a specific geographic area for a radio service, which may be relatively fixed or may change over time. A cell may be further divided into cell sectors. For example, the cell associated with base station 114a may be divided into three sectors. Therefore, in one embodiment, base station 114a may include three transceivers, i.e., one transceiver for each sector of the cell. In one embodiment, base station 114a may employ multiple-input multiple-output (MIMO) technology, and multiple transceivers may be used for each sector of the cell. For example, beamforming can be used to transmit and / or receive signals in a desired spatial direction.

[0019] Base stations 114a and 114b can communicate with one or more of WTRUs 102a, 102b, 102c, and 102d via air interface 116, which can be any suitable wireless communication link (e.g., radio frequency (RF), microwave, centimeter wave, millimeter wave, infrared (IR), ultraviolet (UV), visible light, etc.). Air interface 116 can be established using any suitable radio access technology (RAT).

[0020] More specifically, as noted above, communication system 100 can be a multiple access system and can employ one or more channel access schemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, etc. For example, base station 114a in RAN 104 / 113, and WTRUs 102a, 102b, and 102c can implement radio technologies such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which can use Wideband CDMA (WCDMA) to establish air interfaces 115 / 116 / 117. WCDMA can include communication protocols such as High-Speed ​​Packet Access (HSPA) and / or Evolved HSPA (HSPA+). HSPA can include High-Speed ​​Downlink (DL) Packet Access (HSDPA) and / or High-Speed ​​UL Packet Access (HSUPA).

[0021] In one embodiment, base station 114a and WTRUs 102a, 102b, 102c can implement radio technologies such as Evolved UMTS Terrestrial Radio Access (E-UTRA), which can use Long Term Evolution (LTE) and / or Advanced LTE (LTE-A) and / or Advanced LTE Pro (LTE-A Pro) to establish air interface 116.

[0022] In one embodiment, base station 114a and WTRUs 102a, 102b, 102c can implement radio technologies such as NR radio access, which can use a new radio (NR) to establish an air interface 116.

[0023] In one embodiment, base station 114a and WTRUs 102a, 102b, and 102c can implement multiple radio access technologies. For example, base station 114a and WTRUs 102a, 102b, and 102c can jointly implement LTE radio access and NR radio access, for example, using the dual connectivity (DC) principle. Therefore, the air interface utilized by WTRUs 102a, 102b, and 102c can be characterized by multiple types of radio access technologies and / or transmissions sent to / from multiple types of base stations (e.g., eNBs and gNBs).

[0024] In other embodiments, base station 114a and WTRUs 102a, 102b, 102c can implement the following radio technologies, such as IEEE 802.11 (i.e., WiFi), IEEE 802.16 (i.e., WiMAX), CDMA2000, CDMA2000 1X, CDMA2000 EV-DO, Provisional Standard 2000 (IS-2000), Provisional Standard 95 (IS-95), Provisional Standard 856 (IS-856), Global System for Mobile Communications (GSM), Enhanced Data Rate GSM Evolution (EDGE), GSMEDGE (GERAN), etc.

[0025] Figure 1A Base station 114b can be, for example, a wireless router, a home node B, a home eNode B, or an access point, and can utilize any suitable RAT to facilitate wireless connectivity in a local area, such as a commercial area, home, vehicle, campus, industrial facility, air corridor (e.g., for drone use), road, etc. In one embodiment, base station 114b and WTRUs 102c, 102d can implement radio technologies such as IEEE 802.11 to establish a wireless local area network (WLAN). In one embodiment, base station 114b and WTRUs 102c, 102d can implement radio technologies such as IEEE 802.15 to establish a wireless personal area network (WPAN). In yet another embodiment, base station 114b and WTRUs 102c, 102d can utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, LTE-A Pro, NR, etc.) to establish a picocell or femtocell. Figure 1A As shown, base station 114b may have a direct connection to Internet 110. Therefore, base station 114b may not be required to access Internet 110 via CN 106 / 115.

[0026] RAN 104 / 113 can communicate with CN 106 / 115, which can be any type of network configured to provide voice, data, application, and / or Voice over Internet Protocol (VoIP) services to one or more of WTRUs 102a, 102b, 102c, and 102d. Data may have different Quality of Service (QoS) requirements, such as different throughput requirements, latency requirements, error tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, etc. CN 106 / 115 can provide call control, billing services, location-based services, prepaid calling, internet connectivity, video distribution, and / or perform advanced security functions, such as user authentication. Although... Figure 1AAlthough not shown, it will be understood that RAN104 / 113 and / or CN106 / 115 can communicate directly or indirectly with other RANs that use the same RAT as or a different RAT than RAN 104 / 113. For example, in addition to being connected to RAN 104 / 113, which can utilize NR radio technology, CN106 / 115 can also communicate with another RAN (not shown) that uses GSM, UMTS, CDMA 2000, WiMAX, E-UTRA, or WiFi radio technology.

[0027] CN 106 / 115 may also act as a gateway for WTRU 102a, 102b, 102c, 102d to access PSTN 108, the Internet 110, and / or other networks 112. PSTN 108 may include a circuit-switched telephone network providing Common Old-Style Telephone Service (POTS). The Internet 110 may include a global system of interconnected computer networks and devices using common communication protocols such as Transmission Control Protocol (TCP), User Datagram Protocol (UDP), and / or Internet Protocol (IP) from the TCP / IP Internet Protocol suite. Network 112 may include wired and / or wireless communication networks owned and / or operated by other service providers. For example, network 112 may include another CN connected to one or more RANs, which may use the same RAT as RAN 104 / 113 or a different RAT.

[0028] Some or all of the WTRUs 102a, 102b, 102c, and 102d in communication system 100 may include multi-mode capabilities (e.g., WTRUs 102a, 102b, 102c, and 102d may include multiple transceivers for communicating with different wireless networks via different wireless links). For example, Figure 1A The WTRU 102c shown can be configured to communicate with a base station 114a that can use cellular-based radio technology and a base station 114b that can use IEEE 802 radio technology.

[0029] Figure 1B This is a system diagram illustrating example WTRU 102. (Example:) Figure 1B As shown, WTRU 102 may include a processor 118, a transceiver 120, a transmit / receive element 122, a speaker / microphone 124, a keypad 126, a display / touchpad 128, non-removable memory 130, removable memory 132, a power supply 134, a global positioning system (GPS) chipset 136, and / or other peripherals 138, etc. It will be appreciated that WTRU 102 may include any sub-combination of the above-described elements while remaining consistent with the embodiments.

[0030] Processor 118 may be a general-purpose processor, a special-purpose processor, a conventional processor, a digital signal processor (DSP), multiple microprocessors, one or more microprocessors associated with a DSP core, a controller, a microcontroller, an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA) circuit, any other type of integrated circuit (IC), a state machine, etc. Processor 118 may perform signal encoding, data processing, power control, input / output processing, and / or any other functions that enable WTRU 102 to operate in a wireless environment. Processor 118 may be coupled to transceiver 120, which may be coupled to transmitting / receiving element 122. Although... Figure 1B The processor 118 and transceiver 120 are depicted as separate components, but it will be understood that the processor 118 and transceiver 120 can be integrated together in an electronic package or chip.

[0031] Transmitting / receiving element 122 can be configured to transmit signals to or receive signals from a base station (e.g., base station 114a) via air interface 116. For example, in one embodiment, transmitting / receiving element 122 can be an antenna configured to transmit and / or receive RF signals. In one embodiment, transmitting / receiving element 122 can be a transmitter / detector configured to transmit and / or receive, for example, IR, UV, or visible light signals. In yet another embodiment, transmitting / receiving element 122 can be configured to transmit and / or receive both RF and optical signals. It will be appreciated that transmitting / receiving element 122 can be configured to transmit and / or receive any combination of wireless signals.

[0032] Although the transmitting / receiving element 122 is in Figure 1B While depicted as a single element, WTRU 102 may include any number of transmitting / receiving elements 122. More specifically, WTRU 102 may employ MIMO technology. Thus, in one embodiment, WTRU 102 may include two or more transmitting / receiving elements 122 (e.g., multiple antennas) for transmitting and receiving wireless signals via air interface 116.

[0033] Transceiver 120 can be configured to modulate signals to be transmitted by transmitting / receiving element 122 and demodulate signals received by transmitting / receiving element 122. As noted above, WTRU 102 can have multi-mode capability. Thus, for example, transceiver 120 may include multiple transceivers for enabling WTRU 102 to communicate via multiple RATs (such as NR and IEEE 802.11).

[0034] The processor 118 of WTRU 102 can be coupled to the speaker / microphone 124, keypad 126, and / or display / touchpad 128 (e.g., a liquid crystal display (LCD) unit or an organic light-emitting diode (OLED) display unit), and can receive user input data from them. The processor 118 can also output user data to the speaker / microphone 124, keypad 126, and / or display / touchpad 128. Additionally, the processor 118 can access information from any type of suitable memory (such as non-removable memory 130 and / or removable memory 132), and store data in that memory. Non-removable memory 130 may include random access memory (RAM), read-only memory (ROM), hard disk, or any other type of memory storage device. Removable memory 132 may include a subscriber identity module (SIM) card, memory stick, secure digital storage (SD) card, etc. In other embodiments, processor 118 may access information from memory that is not physically located on WTRU 102 (such as on a server or home computer (not shown)) and store data in that memory.

[0035] The processor 118 can receive power from the power supply 134 and can be configured to distribute and / or control the power going to other components in the WTRU 102. The power supply 134 can be any suitable device for powering the WTRU 102. For example, the power supply 134 may include one or more dry cell batteries (e.g., nickel-cadmium (NiCd), nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Li-ion), etc.), solar cells, fuel cells, etc.

[0036] The processor 118 may also be coupled to a GPS chipset 136, which may be configured to provide location information (e.g., longitude and latitude) about the current location of the WTRU 102. In addition to, or instead of, information from the GPS chipset 136, the WTRU 102 may receive location information from base stations (e.g., base stations 114a, 114b) via air interface 116 and / or determine its location based on the timing of signals received from two or more nearby base stations. It will be understood that the WTRU 102 may acquire location information using any suitable location determination method, while remaining consistent with the embodiments.

[0037] The processor 118 may be further coupled to other peripherals 138, which may include one or more software and / or hardware modules providing additional features, functions, and / or wired or wireless connectivity. For example, peripherals 138 may include accelerometers, electronic compasses, satellite transceivers, digital cameras (for photos and / or videos), Universal Serial Bus (USB) ports, vibration devices, television transceivers, hands-free headsets, Bluetooth® modules, FM radio units, digital music players, media players, video game player modules, internet browsers, virtual reality and / or augmented reality (VR / AR) devices, activity trackers, etc. Peripherals 138 may include one or more sensors, which may be one or more of the following: gyroscopes, accelerometers, Hall effect sensors, magnetometers, orientation sensors, proximity sensors, temperature sensors, time sensors, geolocation sensors, altimeters, light sensors, touch sensors, magnetometers, barometers, gesture sensors, biometric sensors, and / or humidity sensors.

[0038] WTRU 102 may include a full-duplex radio, for which the transmission and reception of some or all signals (e.g., associated with specific subframes for both UL (e.g., for transmission) and downlink (e.g., for reception)) may be concurrent and / or simultaneous. The full-duplex radio may include an interference management unit 139 to reduce and / or substantially eliminate self-interference via signal processing performed via hardware (e.g., a choke) or via a processor (e.g., a separate processor (not shown) or via processor 118). In one embodiment, WTRU 102 may include a half-duplex radio, for which the transmission and reception of some or all signals (e.g., associated with specific subframes for UL (e.g., for transmission) or downlink (e.g., for reception)) may be concurrent and / or simultaneous.

[0039] Figure 1C The diagram illustrates a system diagram of RAN 104 and CN 106 according to an embodiment. As noted above, RAN 104 can employ E-UTRA radio technology to communicate with WTRUs 102a, 102b, and 102c via air interface 116. RAN 104 can also communicate with CN 106.

[0040] RAN 104 may include eNode-Bs 160a, 160b, and 160c, although it will be understood that RAN 104 may include any number of eNode-Bs while remaining consistent with the embodiments. eNode-Bs 160a, 160b, and 160c may each include one or more transceivers for communicating with WTRUs 102a, 102b, and 102c via air interface 116. In one embodiment, eNode-Bs 160a, 160b, and 160c may implement MIMO technology. Therefore, eNode-B 160a may, for example, use multiple antennas to transmit radio signals to and / or receive radio signals from WTRU 102a.

[0041] Each of the eNode-B 160a, 160b, and 160c can be associated with a specific cell (not shown) and can be configured to handle radio resource management decisions, handover decisions, and user scheduling in the UL and / or DL, etc. Figure 1C As shown, eNode-B 160a, 160b, and 160c can communicate with each other via the X2 interface.

[0042] Figure 1C The CN 106 shown may include a Mobility Management Entity (MME) 162, a Serving Gateway (SGW) 164, and a Packet Data Network (PDN) Gateway (or PGW) 166. Although each of the foregoing elements is depicted as part of CN 106, it will be understood that any of these elements may be owned and / or operated by an entity other than a CN operator.

[0043] The MME 162 can connect to each of the eNode-Bs 162a, 162b, and 162c in RAN104 via the S1 interface and can act as a control node. For example, the MME 162 can be responsible for authenticating users of WTRUs 102a, 102b, and 102c, activating / deactivating bearers, and selecting a specific serving gateway during the initial attachment of WTRUs 102a, 102b, and 102c. The MME 162 can provide control plane functions for handover between RAN104 and other RANs (not shown) employing other radio technologies, such as GSM and / or WCDMA.

[0044] The SGW 164 can connect to each of the eNode Bs 160a, 160b, and 160c in RAN104 via the S1 interface. The SGW 164 can typically route and forward user data packets to / from WTRUs 102a, 102b, and 102c. The SGW 164 can perform other functions, such as anchoring the user plane during inter-eNode B handover, triggering paging when DL data is available for WTRUs 102a, 102b, and 102c, and managing and storing the context of WTRUs 102a, 102b, and 102c.

[0045] SGW 164 can be connected to PGW 166, which can provide WTRU 102a, 102b, 102c with access to packet-switched networks (such as Internet 110) to facilitate communication between WTRU 102a, 102b, 102c and IP-enabled devices.

[0046] CN 106 facilitates communication with other networks. For example, CN 106 can provide WTRUs 102a, 102b, and 102c with access to a circuit-switched network (such as PSTN 108) to facilitate communication between WTRUs 102a, 102b, and 102c and conventional terrestrial line communication equipment. For example, CN 106 may include or communicate with an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that acts as an interface between CN 106 and PSTN 108. Additionally, CN 106 can provide WTRUs 102a, 102b, and 102c with access to other networks 112, which may include other wired and / or wireless networks owned and / or operated by other service providers.

[0047] Despite WTRU in Figures 1A to 1D While described as a wireless terminal, it is envisioned that, in some representative embodiments, such a terminal may use (e.g., temporarily or permanently) a wired communication interface with a communication network.

[0048] In a representative embodiment, the other network 112 may be a WLAN.

[0049] In an Infrastructure Basic Services Set (BSS) mode, a WLAN may have an access point (AP) for the BSS and one or more stations (STAs) associated with the AP. The AP may have access or an interface to a distribution system (DS) or another type of wired / wireless network that carries traffic into and / or out of the BSS. Traffic originating outside the BSS destined for a STA can be delivered to the STA via the AP. Traffic from a STA to a destination outside the BSS can be sent to the AP for delivery to the appropriate destination. Traffic between STAs within the BSS can be sent via the AP, for example, where a source STA can send traffic to the AP, and the AP can deliver the traffic to the destination STA. Traffic between STAs within the BSS can be considered and / or referred to as peer-to-peer traffic. Peer-to-peer traffic can be sent between source and destination STAs (e.g., directly between them) using a direct link setup (DLS). In some representative embodiments, the DLS may use 802.11e DLS or 802.11z Tunneled DLS (TDLS). A WLAN using the Standalone BSS (IBSS) mode may not have an access point (AP), and STAs within or using the IBSS (e.g., all STAs) can communicate directly with each other. The IBSS communication mode may sometimes be referred to as a "self-organizing" communication mode in this document.

[0050] When operating in 802.11ac infrastructure mode or a similar mode, the AP can transmit beacons on a fixed channel, such as a primary channel. The primary channel can be of fixed width (e.g., a 20 MHz bandwidth) or dynamically set via signaling. The primary channel can be the operating channel of the BSS and can be used by STAs to establish connections with the AP. In some representative embodiments, Carrier Sense Multiple Access (CSMA / CA) with collision avoidance can be implemented, for example, in an 802.11 system. For CSMA / CA, STAs including the AP (e.g., each STA) can sense the primary channel. If the primary channel is sensed / detected and / or determined to be busy by a particular STA, that STA can back off. A STA can transmit at any given time within a given BSS.

[0051] High-throughput (HT) STAs can communicate using a 40MHz wide channel, for example, by combining a primary 20MHz channel with adjacent or non-adjacent 20MHz channels to form a 40MHz wide channel.

[0052] Very High Throughput (VHT) STAs can support channels with widths of 20MHz, 40MHz, 80MHz, and / or 160MHz. 40MHz and / or 80MHz channels can be formed by combining consecutive 20MHz channels. A 160MHz channel can be formed by combining eight consecutive 20MHz channels or by combining two non-consecutive 80MHz channels (which can be referred to as an 80+80 configuration). For the 80+80 configuration, after channel coding, data is transmitted via a segment resolver that divides the data into two streams. Inverse Fast Fourier Transform (IFFT) processing and time-domain processing can be performed separately on each stream. The streams can be mapped onto two 80MHz channels, and the data can be transmitted by the transmitting STA. At the receiver of the receiving STA, the above operations for the 80+80 configuration can be reversed, and the combined data can be sent to the Media Access Control (MAC).

[0053] Operating modes below 1 GHz are supported by 802.11af and 802.11ah. The channel operating bandwidth and carrier are reduced in 802.11af and 802.11ah compared to those used in 802.11n and 802.11ac. 802.11af supports 5 MHz, 10 MHz, and 20 MHz bandwidths in the TV white space (TVWS) spectrum, while 802.11ah supports 1 MHz, 2 MHz, 4 MHz, 8 MHz, and 16 MHz bandwidths using non-TVWS spectrum. According to representative embodiments, 802.11ah can support instrument-type control / machine-type communications, such as MTC devices in macro coverage areas. MTC devices may have certain capabilities, such as limited capabilities, including support for certain and / or limited bandwidths. MTC devices may include batteries with a lifespan exceeding a threshold (e.g., to maintain a very long battery life).

[0054] WLAN systems that can support multiple channels and channel bandwidths (such as 802.11n, 802.11ac, 802.11af, and 802.11ah) include a channel that can be designated as the primary channel. The primary channel can have a bandwidth equal to the maximum common operating bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel can be set and / or limited by the STA that supports the minimum bandwidth operating mode among all STAs operating in the BSS. In the 802.11ah example, for a STA supporting a 1MHz mode (e.g., an MTC type device), the primary channel can be 1MHz wide, even if the AP and other STAs in the BSS support 2MHz, 4MHz, 8MHz, 16MHz, and / or other channel bandwidth operating modes. Carrier sensing and / or Network Allocation Vector (NAV) settings can depend on the status of the primary channel. If the primary channel is busy, for example because an STA (which supports 1MHz operating mode) is transmitting to the AP, the entire available band may be considered busy, even if most of the band is still idle and available.

[0055] In the United States, the available frequency band for 802.11ah is from 902MHz to 928MHz. In South Korea, the available frequency band is from 917.5MHz to 923.5MHz. In Japan, the available frequency band is from 916.5MHz to 927.5MHz. Depending on the country code, the total available bandwidth for 802.11ah is 6MHz to 26MHz.

[0056] Figure 1D The diagram illustrates a system diagram of RAN 113 and CN 115 according to an embodiment. As noted above, RAN 113 may employ NR radio technology to communicate with WTRUs 102a, 102b, and 102c via air interface 116. RAN 113 may also communicate with CN 115.

[0057] RAN 113 may include gNBs 180a, 180b, and 180c, although it will be understood that RAN 113 may include any number of gNBs while remaining consistent with the embodiments. gNBs 180a, 180b, and 180c may each include one or more transceivers for communicating with WTRUs 102a, 102b, and 102c via air interface 116. In one embodiment, gNBs 180a, 180b, and 180c may implement MIMO technology. For example, gNBs 180a and 180b may utilize beamforming to transmit signals to and / or receive signals from gNBs 180a, 180b, and 180c. Therefore, gNB 180a may, for example, use multiple antennas to transmit radio signals to and / or receive radio signals from WTRU 102a. In one embodiment, gNBs 180a, 180b, and 180c can implement carrier aggregation technology. For example, gNB 180a can transmit multiple component carriers to WTRU 102a (not shown). A subset of these component carriers can be on unlicensed spectrum, while the remaining component carriers can be on licensed spectrum. In one embodiment, gNBs 180a, 180b, and 180c can implement Cooperative Multipoint (CoMP) technology. For example, WTRU 102a can receive cooperative transmissions from gNBs 180a and 180b (and / or gNB 180c).

[0058] WTRUs 102a, 102b, and 102c can communicate with gNBs 180a, 180b, and 180c using transmissions associated with scalable digitization. For example, OFDM symbol spacing and / or OFDM subcarrier spacing can vary depending on different transmissions, different cells, and / or different portions of the radio transmission spectrum. WTRUs 102a, 102b, and 102c can communicate with gNBs 180a, 180b, and 180c using subframes of various or scalable lengths or transmission time intervals (TTIs) (e.g., containing different numbers of OFDM symbols and / or absolute times of varying durations).

[0059] gNBs 180a, 180b, and 180c can be configured to communicate with WTRUs 102a, 102b, and 102c in standalone and / or non-standalone configurations. In standalone configuration, WTRUs 102a, 102b, and 102c can communicate with gNBs 180a, 180b, and 180c without also accessing other RANs (e.g., eNode-Bs 160a, 160b, and 160c). In standalone configuration, WTRUs 102a, 102b, and 102c can utilize one or more of gNBs 180a, 180b, and 180c as mobility anchors. In standalone configuration, WTRUs 102a, 102b, and 102c can communicate with gNBs 180a, 180b, and 180c using signals in unlicensed frequency bands. In a non-standalone configuration, WTRUs 102a, 102b, and 102c can communicate with / connect to gNBs 180a, 180b, and 180c, and simultaneously communicate with / connect to another RAN (such as eNode-Bs 160a, 160b, and 160c). For example, WTRUs 102a, 102b, and 102c can implement DC principles to communicate substantially simultaneously with one or more gNBs 180a, 180b, and 180c and one or more eNode-Bs 160a, 160b, and 160c. In a non-standalone configuration, eNode-B 160a, 160b, and 160c can act as mobility anchors for WTRU 102a, 102b, and 102c, and gNB 180a, 180b, and 180c can provide additional coverage and / or throughput to serve WTRU 102a, 102b, and 102c.

[0060] Each of gNBs 180a, 180b, and 180c can be associated with a specific cell (not shown) and can be configured to handle radio resource management decisions, handover decisions, user scheduling in UL and / or DL, network slicing support, dual connectivity, interoperability between NR and E-UTRA, routing of user plane data to User Plane Functions (UPF) 184a and 184b, routing of control plane information to Access and Mobility Management Functions (AMF) 182a and 182b, etc. Figure 1D As shown, gNB 180a, 180b, and 180c can communicate with each other via the Xn interface.

[0061] Figure 1DThe CN 115 shown may include at least one AMF 182a, 182b, at least one UPF 184a, 184b, at least one Session Management Function (SMF) 183a, 183b, and possibly a Data Network (DN) 185a, 185b. Although each of the foregoing elements is depicted as part of the CN 115, it will be understood that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0062] AMF 182a and 182b can connect to one or more of the gNBs 180a, 180b, and 180c in RAN 113 via the N2 interface and can act as control nodes. For example, AMF 182a and 182b can be responsible for authenticating users of WTRU 102a, 102b, and 102c, supporting network slicing (e.g., handling different PDU sessions with different requirements), selecting specific SMF183a and 183b, managing registration areas, terminating NAS signaling, mobility management, etc. Network slices can be used by AMF182a and 182b to customize CN support for WTRU 102a, 102b, and 102c based on the service types utilized by WTRU 102a, 102b, and 102c. For example, different network slices can be built for different use cases, such as services that rely on Ultra Reliable Low Latency (URLLC) access, services that rely on Enhanced Massive Mobile Broadband (eMBB) access, and services for Machine Type Communication (MTC) access. AMF 162 can provide control plane functions for handover between RAN 113 and other RANs (not shown) employing other radio technologies, such as LTE, LTE-A, LTE-A Pro, and / or non-3GPP access technologies, such as WiFi.

[0063] SMFs 183a and 183b can connect to AMFs 182a and 182b in CN 115 via the N11 interface. SMFs 183a and 183b can also connect to UPFs 184a and 184b in CN 115 via the N4 interface. SMFs 183a and 183b can select and control UPFs 184a and 184b, and configure traffic routing through UPFs 184a and 184b. SMFs 183a and 183b can perform other functions, such as managing and allocating WTRU IP addresses, managing PDU sessions, controlling policy enforcement and QoS, and providing downlink data notifications. PDU session types can be IP-based, non-IP-based, Ethernet-based, etc.

[0064] UPF 184a and 184b can connect to one or more of gNBs 180a, 180b, and 180c in RAN 113 via the N3 interface. These gNBs can provide WTRU 102a, 102b, and 102c with access to a packet-switched network (such as the Internet 110) to facilitate communication between WTRU 102a, 102b, 102c and IP-enabled devices. UPF 184a and 184b can perform other functions such as routing and forwarding packets, enforcing user plane policies, supporting multi-homed PDU sessions, handling user plane QoS, buffering downlink packets, and providing mobility anchoring.

[0065] CN 115 can facilitate communication with other networks. For example, CN 115 may include or communicate with an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that acts as an interface between CN 115 and PSTN 108. Additionally, CN 115 can provide WTRUs 102a, 102b, and 102c with access to other networks 112, which may include other wired and / or wireless networks owned and / or operated by other service providers. In one embodiment, WTRUs 102a, 102b, and 102c can connect to local data networks (DNs) 185a and 185b via the N3 interface to UPFs 184a and 184b and the N6 interface between UPFs 184a and 184b and DNs 185a and 185b.

[0066] Given Figures 1A to 1D as well as Figures 1A to 1D The corresponding descriptions may be performed by one or more emulation devices (not shown) to perform one or more of the functions described herein with respect to one or more of the following: WTRU102a-d, base station 114a-b, eNode-B160a-c, MME 162, SGW 164, PGW 166, gNB180a-c, AMF 182a-ab, UPF 184a-b, SMF 183a-b, DN 185a-b, and / or one or more other devices described herein. An emulation device may be one or more devices configured to emulate one or more of the functions described herein. For example, an emulation device may be used to test other devices and / or simulate network and / or WTRU functions.

[0067] Simulation devices can be designed to perform tests on one or more other devices in a laboratory environment and / or a carrier network environment. For example, the one or more simulation devices can perform one or more or all of their functions while being fully or partially implemented and / or deployed as part of a wired and / or wireless communication network to test other devices within the communication network. The one or more simulation devices can perform one or more or all of their functions while being temporarily implemented / deployed as part of a wired and / or wireless communication network. Simulation devices can be directly coupled to another device for testing purposes and / or can use over-the-air wireless communication to perform tests.

[0068] The one or more simulation devices can perform one or more (including all) functions without being implemented / deployed as part of a wired and / or wireless communication network. For example, the simulation devices can be used in test scenarios in a test laboratory and / or in non-deployed (e.g., testing) wired and / or wireless communication networks to perform testing on one or more components. The one or more simulation devices can be test rigs. Direct RF coupling and / or wireless communication via RF circuitry (e.g., which may include one or more antennas) can be used by the simulation devices to transmit and / or receive data.

[0069] Beam management can be implemented as one of the target use cases for AI / ML in air interfaces. This technique can improve performance and / or complexity in traditional beam management aspects, including beam prediction in the temporal and / or spatial domains for purposes such as reducing overhead and latency, improving beam selection accuracy, etc.

[0070] In traditional NR, the gNB can select the set of SS / PBCH blocks (SSBs) to be transmitted in an SSB burst, where the list of SSBs to be transmitted in the SSB burst can be indicated via ssb-PositionsInBurst (ssb - position in the burst) in SIB1. Transmitting SSB beams (e.g., up to 64) can result in relatively large payload and / or overhead for the gNB. It can impact system performance and latency when the number of transmitted SSBs can be reduced. Therefore, the gNB can skip the transmission of some SSBs and transmit a subset of SSBs, and the WTRU can predict (e.g., using an AIML system) the optimal beam based on the transmitted SSBs. An example of this scenario is... Figure 2The diagram illustrates the transmission of a subset of the gNB beam (shown as solid line beams) and the skipping of a subset of the beam (shown as dashed line beams). This results in different WTRU behaviors during SSB beam prediction and subsequent initial access procedures. The WTRU may need to determine inputs, conditions, measurements, etc., for inference, verification, etc. Therefore, this paper describes embodiments related to SSB skipping and enhancements in NR AI / ML beam management.

[0071] The WTRU can efficiently perform initial access in a system with skipped SSBs. This document describes an embodiment of initial access in an AIML scenario with skipped SSBs. In one example, the WTRU can be configured with a set of transmitted SSB beams and a set of predicted SSB beams. The WTRU can select the predicted beams for which it performs initial access (e.g., based on the predicted RSRP). The WTRU can initiate initial access by transmitting a PRACH preamble on a PRACH resource, where the PRACH resource can be selected based on one or more of the following: associated detected SSB beams, predicted SSB beams, and / or a combination of multiple detected and / or predicted SSB beams. To perform initial access in an AIML system with skipped SSBs, a process for predicting SSB beams in the system with skipped SSBs can be performed (e.g., using sets A and B in the system with skipped SSBs, as further described herein). PRACH preamble transmission can be performed in an AIML scenario with skipped SSBs.

[0072] In one embodiment, the WTRU can initiate initial access by transmitting a PRACH preamble on a PRACH resource, which can be selected based on an associated detected SSB beam or an actually transmitted SSB. For example, the WTRU can be configured to transmit a PRACH preamble on a resource corresponding to an associated detected SSB beam. The WTRU can indicate the preferred predicted beam to the gNB in ​​accordance with the PRACH preamble selection, Msg3 transmission, or a transmission performed after the RA procedure. In the RAR, for example, the gNB can indicate whether the predicted beam is accepted (by transmitting the same RAPID (preamble ID) or another ID to instruct the WTRU to select another beam (either the detected beam or the predicted beam)). This can be applicable, for example, in situations where the gNB does not transmit SSBs due to gNB implementation (e.g., the gNB shuts down those beams for power enhancement). For example, the gNB may also not want to receive anything at those beams. The gNB may not use the beam unless requested by the WTRU.

[0073] The WTRU can initiate initial access by transmitting a PRACH preamble on a PRACH resource, which can be selected based on a predicted SSB beam or skipped SSBs. For example, the WTRU can be configured to transmit a PRACH preamble on a resource corresponding to one of the predicted SSB beams (e.g., the one with the highest RSRP). The WTRU can be configured to use one or more random access parameters (e.g., for PRACH transmission and RAR reception, such as the number of retransmissions of the PRACH preamble, power ramp rise, etc.).

[0074] The WTRU can initiate initial access by transmitting a PRACH preamble on a PRACH resource, which can be selected based on a combination of multiple detected and / or predicted SSB beams or a combination of actually transmitted SSBs and skipped SSBs. For example, the WTRU can be configured to transmit a PRACH preamble on multiple resources corresponding to the detection and / or prediction of more than one SSB beam (e.g., based on a receiving configuration for a detected SSB, such as in the direction of the detected SSB). For example, a first resource can indicate that both the detected SSB and a first predicted SSB beam are preferred beams, a second resource can indicate that both the detected SSB and a second predicted SSB beam are preferred beams, and so on. If the gNB receives a PRACH on a resource corresponding to an SSB beam that was not actually transmitted, the gNB can expect that the SSB may have already been selected based on prediction.

[0075] The WTRU can monitor the PDCCH scrambled using RA-RNTI to detect RAR within the periodic RAR window corresponding to the transmitted PRACH and / or the associated detected and / or predicted SSB beam. Upon receiving a RAR, the WTRU can continue with initial access (e.g., transmission of Msg3, etc.).

[0076] This document describes an embodiment of WTRU behavior in the event of a failed PRACH transmission. For example, the WTRU may receive or be configured to receive a set of transmitted SSB beams or actually transmitted SSBs and a set of predicted SSB beams. The predicted SSBs may not be transmitted by the base station. The WTRU can select the predicted beam or SSB (e.g., based on the predicted RSRP), for which it can perform initial access (e.g., PRACH preamble transmission). The WTRU can use the beam associated with the predicted beam or predicted SSB to transmit a PRACH preamble or random access preamble. In one example, the WTRU can monitor PDCCH scrambled using RA-RNTI scheduled for RAR to detect RAR within a periodic RAR window corresponding to the transmitted PRACH and / or the associated detected and / or predicted SSB beams. If the WTRU receives a RAR, it can continue with initial access (e.g., transmission of Msg3, etc.). If the WTRU does not receive a RAR within the configured time window or based on a counter, the WTRU may employ one or more of the following methods. In one method, the WTRU may switch the SSB beam to another SSB beam from a list of predicted SSB beams, and so on up to k beams (e.g., selected in descending order of RSRP), or select another predicted SSB and transmit a random access preamble using the beam associated with that other predicted SSB. The set of predicted SSBs may be sorted in descending order of Reference Signal Received Power (RSRP), and a predicted SSB may be selected from the sorted list. In one method, the WTRU may transmit (e.g., only) a PRACH for the detected beam, or select the actually transmitted SSB and transmit a random access preamble using the beam associated with the actually transmitted SSB. In one method, the WTRU may wait for a conventional SSB burst for each transmitted SSB beam, or receive subsequent SSB bursts. For example, a gNB may have SSB bursts for each anticipated SSB beam (ssb-SetA) that might be transmitted using a longer period. For instance, after M SSB bursts for skipped SSB beams, the gNB will transmit an SSB burst for each of the transmitted anticipated beams. Subsequent SSB bursts may include both the actual transmitted SSB and the actual transmission of the predicted SSB. Therefore, based on subsequent SSB bursts, the WTRU can wait for the maximum duration of M SSB bursts (e.g., M is configured in the MIB or SIB1) and then accordingly detect or select the best SSB beam or a new SSB for initial access. In one approach, the WTRU may reject the cell and attempt to detect or select another SSB block in a different synchronization grating and / or another cell for initial access.

[0077] This document describes an embodiment of the correction and confirmation process for a predicted beam based on a received RAR. For example, the WTRU can determine that the predicted SSB beam is the optimal beam based on the detected and / or received SSB beam and an AIML model (e.g., based on the predicted RSRP). The WTRU can initiate the initial access procedure by sending a PRACH preamble for the predicted SSB beam (e.g., in the time and frequency resources associated with the predicted SSB beam). The WTRU can monitor to receive the RAR within the RAR window.

[0078] In one example, after receiving a RAR (e.g., a RAR PDCCH and / or RAR PDSCH on the beam of the predicted SSB beam QCL), the WTRU can measure the RSRP (e.g., based on a reference signal in the RAR message, such as DMRS). The WTRU can then compare the measured RSRP based on the received RAR with the predicted RSRP for the predicted SSB. For example, the WTRU can be configured or receive (e.g., via MIB, SIB1, and / or RAR) one or more parameters related to an offset and / or threshold for comparing the RSRP measured based on the RAR (e.g., PDCCH, DMRS, or PDSCH DMRS) with the predicted RSRP for the SSB. The motivation here could be, for example, that the RSRP measured from the SSB and DMRS are different. Moreover, the transmit power for the SSB and DMRS can have a large difference. Therefore, the gNB can provide an offset / threshold (e.g., 10 dB) for comparison.

[0079] In one example, the WTRU can verify the accuracy of the prediction based on comparison and one or more of an offset or threshold (e.g., determining whether the difference between the predicted RSRP and the measured RSRP is below a threshold (e.g., 10 dB)). For example, if the difference between the predicted RSRP and the measured RSRP is below a (pre)configured threshold, the WTRU can determine that the predicted beam is sufficiently accurate and can therefore continue to be used for the transmission of further signals (e.g., Msg3). For example, if the difference between the predicted RSRP and the measured RSRP is above a (pre)configured threshold, the WTRU can determine that the predicted beam is not sufficiently accurate. The WTRU can reject the predicted beam and continue to select another beam or follow the process considered for failed PRACH transmissions.

[0080] In one example, (e.g., alternatively) where the WTRU has already transmitted PRACH based on a combination of multiple (e.g., two) detected and / or predicted SSB beams (as discussed further herein), the WTRU can receive multiple (e.g., two) RAR messages for corresponding beams. For example, the WTRU can measure the RSRP for each of the received RAR messages and determine the optimal beam (e.g., one with a higher RSRP). The WTRU can then transmit further signals (e.g., Msg3) based on the selected optimal beam.

[0081] For the embodiments proposed herein, there are aspects common to all embodiments as described below. Artificial intelligence (AI) can be defined as behavior exhibited by a machine. Such behavior can, for example, mimic cognitive functions used for sensing, reasoning, adaptation, and action. Machine learning (ML) can refer to the type of algorithm that solves problems based on learning through experience ("data") without being explicitly programmed ("configuration set of rules"). Machine learning can be considered a subset of AI. Different machine learning paradigms can be conceived based on the nature of the data or feedback available to the learning algorithm. For example, supervised learning schemes may involve: learning the ability to map inputs to outputs based on labeled training examples, where each training example can be a pair consisting of an input and a corresponding output. For example, unsupervised learning schemes may involve: detecting patterns in data that do not have pre-existing labels. For example, reinforcement learning schemes may involve: executing sequences of actions in an environment to maximize cumulative rewards. In some solutions, it is possible to apply machine learning algorithms using combinations or interpolations of the schemes mentioned above. For example, semi-supervised learning schemes may use a combination of a small amount of labeled data and a large amount of unlabeled data during training. In this respect, semi-supervised learning falls between unsupervised learning (without labeled training data) and supervised learning (with labeled training data). Deep learning (DL) can refer to a class of machine learning algorithms that employ artificial neural networks (specifically, DNNs) loosely inspired by biological systems. Deep neural networks (DNNs) are a special class of machine learning models inspired by the human brain, where the input is linearly transformed and passed through a non-linear activation function multiple times. DNNs typically consist of multiple layers, each consisting of a linear transformation and a given non-linear activation function. DNNs can be trained using training data via a backpropagation algorithm. Recently, DNNs have demonstrated state-of-the-art performance in various domains (e.g., voice, vision, natural language, etc.) and against various machine learning settings, including supervised, unsupervised, and semi-supervised methods. The term AIML-based methods / processes can refer to the implementation of behavior and / or compliance with requirements through data-based learning without explicit configuration of a sequence of action steps. This approach enables the learning of complex behaviors that might be difficult to specify and / or implement using conventional methods.

[0082] A WTRU can transmit or receive physical channels or reference signals based on at least one spatial domain filter. The term "beam" can be used to refer to a spatial domain filter. A WTRU can transmit physical channels or signals using the same spatial domain filter used to receive RS (such as CSI-RS) or SS blocks. The WTRU transmission can be referred to as the "target," and the received RS or SS block can be referred to as the "reference" or "source." In this case, the WTRU can be said to transmit the target physical channel or signal based on a spatial relationship with a reference to such RS or SS block. A WTRU can transmit a first physical channel or signal based on the same spatial domain filter used to transmit a second physical channel or signal. The first and second transmissions can be referred to as the "target" and "reference" (or "source"), respectively. In this case, the WTRU can be said to transmit the first (target) physical channel or signal based on a spatial relationship with a reference to a second (reference) physical channel or signal. The spatial relationship can be implicit, configured by RRC, or signaled by MAC CE or DCI. For example, the WTRU can implicitly transmit the DM-RS of the PUSCH and PUSCH based on the same spatial domain filter as the SRS indicated by the SRI configured by the RRC or indicated in the DCI. In another example, the spatial relationship can be configured by the RRC for the SRS Resource Indicator (SRI) or signaled by the MAC CE for the PUCCH. This spatial relationship can also be referred to as "beam indication". The WTRU can receive the first (target) downlink channel or signal based on the same spatial domain filter or spatial reception parameters as the second (reference) downlink channel or signal. For example, this association can exist between a physical channel such as the PDCCH or PDSCH and its corresponding DM-RS. This association can exist between corresponding antenna ports, at least when the first and second signals are reference signals, and when the WTRU is configured with a Quasi-Coordination (QCL) assumption type D. This association can be configured as a TCI (Transmit Configuration Indicator) state. The association between the CSI-RS or SS block and the DM-RS can be indicated to the WTRU by indexing the set of TCI states configured by the RRC and / or signaled by the MAC CE. This type of indication can also be called a "beam indicator".

[0083] In this document, a TRP (e.g., a transmit and receive point) may be used interchangeably with one or more of TP (transmit point), RP (receive point), RRH (radio remote head), DA (distributed antenna), BS (base station), (BS's) sector, and / or cell (e.g., a geographic cell area served by the BS). In this document, multiple TRPs may be used interchangeably with one or more of MTRP, M-TRP, and multiple TRPs.

[0084] The WTRU can report a subset of Channel State Information (CSI) components, which may correspond at least to the CSI-RS Resource Indicator (CRI), SSB Resource Indicator (SSBRI), indications of the receiving panel at the WTRU (such as panel identity or group identity), measurement results obtained from the SSB or CSI-RS such as L1-RSRP, L1-SINR (e.g., cri-RSRP, cri-SINR, ssb-Index-RSRP, ssb-Index-SINR), and other channel state information such as at least rank indicator (RI), channel quality indicator (CQI), precoding matrix indicator (PMI), layer index (LI), etc.

[0085] The WTRU can receive synchronization signal / physical broadcast channel (SS / PBCH) blocks. An SS / PBCH block (SSB) can include the primary synchronization signal (PSS), secondary synchronization signal (SSS), and physical broadcast channel (PBCH). The WTRU can monitor, receive, or attempt to decode SSBs during initial access, initial synchronization, radio link surveillance (RLM), cell search, cell handover, and other processes.

[0086] The WTRU can measure and report Channel State Information (CSI), wherein the CSI for each connectivity mode can include or be configured with one or more of the following: CSI reporting configuration, including one or more of the following: CSI reporting configuration, CSI-RS resource set, and / or NZP CSI-RS resources. The CSI reporting configuration can include one or more of the following: the number of CSI reports, such as Channel Quality Indicator (CQI), Rank Indicator (RI), Precoding Matrix Indicator (PMI), CSI-RS Resource Indicator (CRI), Layer Indicator (LI), etc.; CSI report type, such as aperiodic, semi-persistent, periodic; CSI report codebook configuration, such as Type I, Type II, Type II port selection, etc.; and / or CSI reporting frequency. The CSI-RS resource set can include one or more of the following: CSI resource settings; NZP-CSI-RS resources for channel measurements; NZP-CSI-RS resources for interference measurements; and / or CSI-IM resources for interference measurements. NZPCSI-RS resources may include one or more of the following: NZP CSI-RS resource ID, periodicity, and offset; QCL information and TCI status; and / or resource mapping (e.g., number of ports, density, CDM type, etc.).

[0087] In one example, the WTRU may indicate, identify, or be configured with one or more reference signals. The WTRU may monitor, receive, and measure one or more parameters based on the corresponding reference signals. For example, one or more of the following may be applicable. The following parameters are non-limiting examples of parameters that may be included in the measurement results of one or more reference signals. One or more of these parameters may be included. Other parameters may be included.

[0088] The SS reference signal received power (SS-RSRP) can be measured based on a synchronization signal (e.g., the demodulated reference signal (DMRS) in the PBCH or SSS). It can be defined as the linear average of the power contribution of the resource element (RE) carrying the corresponding synchronization signal. Power scaling for the reference signal can be required when measuring RSRP. In the case of SS-RSRP used for L1-RSRP, the measurement can be performed based on both the synchronization signal and the CSI reference signal. CSI-RSRP can be measured based on the linear average of the power contribution of the resource element (RE) carrying the corresponding CSI-RS. CSI-RSRP measurement can be configured within the measurement resources for the configured CSI-RS timing. The SS signal-to-noise and interference ratio (SS-SINR) can be measured based on a synchronization signal (e.g., the DMRS in the PBCH or SSS). It can be defined as the linear average of the power contribution of the resource element (RE) carrying the corresponding synchronization signal divided by the linear average of the noise and interference power contributions. In the case of SS-SINR used for L1-SINR, noise and interference power measurements can be performed based on resources configured by higher layers. CSI-SINR can be measured by dividing the linear average of the power contribution of the resource element (RE) carrying the corresponding CSI-RS by the linear average of the noise and interference power contributions. When CSI-SINR is used for L1-SINR, noise and interference power measurements can be performed based on resources configured at higher layers. Otherwise, noise and interference power can be measured based on resources carrying the corresponding CSI-RS.

[0089] Received Signal Strength Indicator (RSSI) can be measured based on the average of the total power contribution across the configured OFDM symbols and bandwidth. The power contribution can be received from different resources (e.g., cooperating channel serving and non-serving cells, adjacent channel interference, thermal noise, etc.). Cross-Layer Interference Received Signal Strength Indicator (CLI-RSSI) can be measured based on the average of the total power contribution across the configured OFDM symbols with configured time and frequency resources. The power contribution can be received from different resources (e.g., cross-layer interference, cooperating channel serving and non-serving cells, adjacent channel interference, thermal noise, etc.). Sounding Reference Signal Receiver Ratio (SRS-RSRP) can be measured based on the linear average of the power contribution of the resource element (RE) carrying the corresponding SRS. Secondary Synchronization Reference Signal Receiver Quality (SS-RSRQ) can be measured based on measurements of Received Signal Power (SS-RSRP) and Received Signal Strength (RSSI). In one example, SS-RSRQ can be calculated as the ratio of N × SS-RSRP / NR carrier RSSI, where N can be determined based on the number of resource blocks within the corresponding NR carrier RSSI measurement bandwidth. Thus, the measurements used in the numerator and denominator can be on the same set of resource blocks. CSI Reference Signal Received Quality (CSI-RSRQ) can be measured based on measurements of Reference Signal Received Power (CSI-RSRP) and Received Signal Strength (RSSI). In one example, SS-RSRQ can be calculated as the ratio of N × CSI-RSRP / CSIRSSI, where N can be determined based on the number of resource blocks within the corresponding CSI-RSSI measurement bandwidth. Thus, the measurements used in the numerator and denominator can be on the same set of resource blocks.

[0090] In one example, a CSI report configuration (e.g., CSI-ReportConfigs) may be associated with a single BWP (e.g., indicated by BWP-Id) where one or more of the following parameters are configured: CSI-RS resources and / or sets of CSI-RS resources for channel and interference measurements; CSI-RS report configuration type, including periodic, semi-persistent, and non-periodic; CSI-RS transmit periodicity for periodic and semi-persistent CSI reports; CSI-RS transmit slot offsets for periodic, semi-persistent, and non-periodic CSI reports; a list of CSI-RS transmit slot offsets for semi-persistent and non-periodic CSI reports; time constraints for channel and interference measurements; report band configuration (wideband / subband CQI, PMI, etc.); thresholds and calculation modes for the number of reports (CQI, RSRP, SINR, LI, RI, etc.); codebook configuration; group-based beam reporting; CQI table; subband size; non-PMI port indication; port index; etc.

[0091] In one example, a CSI-RS resource set (e.g., NZP-CSI-RS-ResourceSet) may include one or more CSI-RS resources (e.g., NZP-CSI-RS-Resource and CSI-ResourceConfig), wherein the WTRU may be configured in the CSI-RS resource with one or more of the following: CSI-RS periodicity and slot offset for periodic and semi-persistent CSI-RS resources; CSI-RS resource mapping for defining the number, density, CDM type, OFDM symbol and subcarrier occupancy of CSI-RS ports; the bandwidth portion to which the configured CSI-RS is allocated; and / or a reference to including one or more QCL source RSs and one or more TCI states of corresponding QCL types.

[0092] In one example, one or more of the following configurations can be used for an RS resource set. For example, a WTRU can be configured with one or more RS resource sets. An RS resource set configuration can include one or more of the following: an RS resource set ID; one or more RS resources for the RS resource set; repetition (e.g., on or off); a non-periodic trigger offset (e.g., one of 0 to 6 slots); and / or TRS information (e.g., true or false).

[0093] One or more of the following configurations can be used for RS resources. For example, a WTRU can be configured with one or more RS resources. RS resource configurations can include one or more of the following: RS resource ID; resource mapping (e.g., RE in PRB); power control offset (e.g., a value of -8, ..., 15); power control offset with SS (e.g., -3 dB, 0 dB, 3 dB, 6 dB); scrambling ID; periodicity and offset; and / or QCL information (e.g., based on TCI status).

[0094] The following characteristics of authorization or assignment may consist of at least one of the following: frequency allocation; time allocation aspects, such as duration; priority; modulation and coding scheme; transport block size; number of spatial layers; number of transport blocks; TCI status, CRI, or SRI; number of repetitions; whether the repetition scheme is type A or type B; whether the authorization is configured as type 1, type 2, or dynamic authorization; whether the assignment is dynamic or semi-persistent scheduling (configuration) assignment; the configured authorization index or semi-persistent assignment index; the periodicity of the configured authorization or assignment; channel access priority class (CAPC); and / or any parameters provided in the DCI, by the MAC, or by the RRC for scheduling authorization or assignment.

[0095] The indications made by DCI can be comprised of at least one of the following: explicit indications made by DCI fields or by RNTI used to mask or scramble the CRC of the DCI; and / or implicit indications made by characteristics such as DCI format, DCI size, kernel set or search space, aggregation level, and the first resource element of the received DCI (e.g., the index of the first control channel element), wherein the mapping between characteristics and values ​​can be signaled by RRC or MAC. The use of RNTI for the reception or monitoring of DCI can imply that the CRC of the DCI is masked or scrambled using RNTI.

[0096] In this document, the signal may be used interchangeably with one or more of the following: sounding reference signal (SRS); channel state information-reference signal (CSI-RS); demodulation reference signal (DM-RS); phase tracking reference signal (PT-RS); and / or synchronization signal block (SSB).

[0097] In this document, the channel may be used interchangeably with one or more of the following: Physical Downlink Control Channel (PDCCH); Physical Downlink Shared Channel (PDSCH); Physical Uplink Control Channel (PUCCH); Physical Uplink Shared Channel (PUSCH); Physical Random Access Channel (PRACH); etc.

[0098] In this document, signals, channels, and messages can be used interchangeably (e.g., as in DL or UL signals, channels, and messages). In this document, RS can be used interchangeably with one or more of RS resources, RS resource sets, RS ports, and RS port groups. In this document, RS can be used interchangeably with one or more of SSB, CSI-RS, SRS and DM-RS, TRS, PRS, and PTRS.

[0099] In this paper, time slots, symbols, and subframes can be used interchangeably. The terms SSB, SS / PBCH block, PSS, SSS, PBCH, and MIB can be used interchangeably. SSB, SSB beam, and SSB index can be used interchangeably. The proposed solution for beam resource prediction in this paper can be used for beam resources belonging to a single or multiple cells and a single or multiple TRPs.

[0100] In this document, CSI reports and CSI measurement results, beam reports and beam measurement results can be used interchangeably. RS resource sets and beam groups can also be used interchangeably.

[0101] The embodiments described herein may share initial common embodiment components, such as, for example: SS / PBCH blocks, MIBs, and SIBs; configuration of measurement and estimation sets; and set B requirements. In one embodiment, the WTRU may receive a Physical Broadcast Channel (PBCH). The PBCH may be part of an SS / PBCH block (SSB). The PBCH may carry system information. The PBCH may include or carry a Master Information Block (MIB). The term MIB may be used to denote the content, information, payload, and / or bits carried by the PBCH. PBCH and MIB may be used interchangeably herein. For example, upon detecting and / or receiving an SS / PBCH block, the WTRU may use information in the MIB on time and / or frequency resources to locate one or more System Information Blocks (SIBs). The term SIB may be used to denote content, information, payload, and / or bits. In one example, one or more cell selection (reselection) parameters may be broadcast in an SIB (e.g., SIB1, SIB2, SIB3, etc.), where the WTRU may detect and / or receive from serving and / or newly detected cells.

[0102] In one embodiment, the WTRU may be configured with one or more sets of reference signal (RS) resources and / or beams (or beam pairs). Each RS resource or beam or beam pair may be associated with the transmission of a beam from specific beam parameters (e.g., beam direction and bandwidth). The WTRU may be configured to associate beams and / or RS resources and beam parameters. In one example, the WTRU may be configured with a first set of RS resources or beams or beam pairs that can cover the entire RS resource space, beam space, or beam pair space. The WTRU may determine or select sets A and B such that the union of sets A and B covers the entire RS resource space, beam space, or beam pair space. In one example, sets A and B may be mutually exclusive. In one example, set B includes the following RS resources: on which WTRU can perform measurements to obtain 1) direct measurements for a first set of beams or beam pairs (e.g., a one-to-one mapping between RS resources and beams or beam pairs) and 2) estimated measurements for a second set of beams or beam pairs (e.g., a many-to-one mapping between RS resources and beams or beam pairs, possibly using an AI / ML estimation model).

[0103] In one embodiment, the WTRU may be configured with one or more sets of RS resources associated with each beam. For example, the WTRU may be configured with a first beam associated with two sets of RS resources: the first set includes a single RS resource and the second set includes multiple RS resources. The WTRU may determine the measurement results associated with the beam via direct measurement results of the RS resources in the first set or via estimation obtained from measurement results of the RS resources in the second set. The WTRU may determine a set of measurements of RS resources (e.g., set B) such that for each beam for which it must obtain its measurement results (directly or via estimation), set B contains at least one of the two sets of RS resources associated with the beam. Hereinafter, set B may be used interchangeably with one or more of the following sets: RS resource set, beam, beam pair, beam RS resource, RS resource and / or beam pattern. Hereinafter, set A may be used interchangeably with one or more of the following sets: RS resource set, beam, beam pair, beam RS resource, RS resource and / or beam pattern.

[0104] Initial access can be performed in an AIML system with skipped SSBs. In one embodiment, a set of SSBs can be determined in a system with skipped SSBs: a specified set A and a set B. The WTRU can be (pre-)configured with a maximum number of SSBs in the cell (e.g., within an SSB burst). The maximum number of SSBs can be explicitly configured for the WTRU (e.g., via MIB, SIB, etc.). Alternatively, the maximum number of SSBs can be implicitly indicated to the WTRU, for example, based on the frequency range used. In one example, if the WTRU operates in a first frequency range (e.g., FR1), the WTRU can determine the maximum number of SSBs within an SSB burst as a first value (e.g., a maximum of eight SSBs); if the WTRU operates in a second frequency range (e.g., FR2), the WTRU can determine the maximum number of SSBs within an SSB burst as a second value (e.g., a maximum of 64 SSBs), and so on.

[0105] The WTRU can detect one or more SSBs within an SSB burst (e.g., during initial access, cell selection (reselection), etc.). In one example, considering the maximum number of SSBs within an SSB burst, a subset of SSBs can actually be planned, configured, required, desired, and / or designed to be used within the SSB burst (e.g., within a cell). The planned set of SSBs can be a set of SSBs that can cover the entire SSB resource space or beam space. In one example, the number of planned SSBs can be less than or equal to the maximum number of SSBs, which is determined at the network based on the SSB coverage space, beam correlation, etc. The WTRU can be provided with and / or configured with the number of planned SSBs and / or corresponding SSB beam indices, where the WTRU can treat the set of planned SSBs as set A.

[0106] The WTRU can receive, be provided with, or be configured with information relating to the SSBs actually transmitted within an SSB burst. This information may include the number of actually transmitted SSB beams, the SSB index corresponding to each transmitted SSB beam, and so on. The WTRU can consider the set of actually transmitted SSBs as set B, where set B may be a subset of the configured set A. In one example, (e.g., alternatively) the WTRU can determine, be provided with, or be configured with a set of skipped SSBs that are a subset of set A not actually transmitted in the corresponding SSB burst. In one example, the union of set B and the set of skipped beams may be equal to set A.

[0107] Figure 2 This is a diagram illustrating an example of a system 200 with skipped SSBs. As an example, such as... Figure 2 As shown, solid-line beams indicate set B as the actual transmitted beams; dashed-line beams indicate skipped beams, and set A is the union of set B and the skipped beams. The terms "transmitted SSB" and "actually transmitted SSB" can be used interchangeably. The terms "untransmitted SSB" and "skipped SSB" can also be used interchangeably.

[0108] A process for predicting SSB beams in a system with skipped SSBs can be performed. In an example solution, the WTRU can perform one or more of the following: The WTRU can detect one or more SSBs (e.g., during initial access) or receive an indication of a set of one or more actually transmitted SSBs in an SSB burst. The WTRU can select a first SSB with the highest received power (e.g., RSRP). The WTRU can determine time and frequency synchronization based on the first SSB. The WTRU can decode the PSS, SSS, PBCH, PBCH-DMRS, SSB index, MIB, and SIB1 for the first SSB. The WTRU can receive a configuration regarding or indicating whether SSB skipping is enabled at the gNB (e.g., via MIB or SIB1), or receive an indication of a set of one or more skipped SSBs in an SSB burst. The WTRU can receive a list (e.g., set A) of each SSB configured by the gNB (e.g., via ssb-SetA in SIB1). The WTRU can receive a list of transmitted SSBs (e.g., set B) (e.g., via ssb-SetB and / or ssb-PositionsInBurst in SIB1). The WTRU can receive configuration information associated with each transmitted SSB (ssb-SetB), including a list of candidate beams (e.g., ssb-candidates) that the WTRU can use as inference input. This includes information about the association of one or more transmitted SSBs with one or more untransmitted SSBs. The candidate beam list can include beams associated with untransmitted SSBs. The set of candidate beams can be indicated for each SSB beam in set B. The configuration information can include beam indices, azimuth, elevation, aiming angles, etc. In one example, for each transmitted SSB beam from ssb-SetB, the WTRU can receive a list of candidate SSB beams (e.g., ssb-candidates) where the candidate beams are a subset of set A. The WTRU can determine which SSB beams are associated (e.g., adjacent, neighboring, or related) with the detected beams from the ssb-SetB based on a candidate SSB beam list (ssb-candidate). The WTRU can use an AIML model to predict a set / list of N (best) predicted SSB beams from a list of never-transmitted SSB beams. The number of predictable beams can depend on the AIML model. The WTRU can use the list of N predicted beams along with the received candidate SSB beam list (e.g., ssb-candidate) to select k best SSB beams. The k best SSB beams in the list can be sorted according to the AIML model for the predicted SSB beams (e.g., descending order based on RSRP, RSRQ, etc.).The set of predicted SSBs can be sorted in descending order of Reference Signal Received Power (RSRP), and the predicted SSB is selected from the sorted list. The WTRU can initiate initial access on PRACH resources (e.g., by transmitting a PRACH preamble). The WTRU can receive one or more information configurations regarding one or more SSB-specific (e.g., beam-specific) parameters (e.g., paging search space, etc.) for the predicted SSB as part of the initial access procedure (e.g., via RAR, Msg4, and / or MsgB). The gNB can know that the WTRU has predicted the predicted SSB based on the received PRACH because the corresponding SSB was not transmitted first.

[0109] The WTRU can support the initial access procedure based on predicted quality (e.g., predicted RSRP) and measured quality (e.g., measured RSRP). The WTRU can detect one or more SSBs (e.g., during initial access) and select a first number of SSBs with the highest quality (e.g., Received Power (RSRP), RSRQ, SINR, Hypothetical BLER, etc.). The first number of SSBs can be determined based on one or more of the following: a quality threshold, a predefined maximum number, and / or UE capabilities.

[0110] The first number of SSBs can be determined based on a quality threshold. For example, the WTRU can identify one or more SSBs with quality higher than a threshold. The threshold can be predetermined or configured (e.g., by the gNB). The first number of SSBs can also be determined based on a predefined maximum number. For example, the maximum number of SSBs identified (e.g., M1) can be predetermined or configured. For example, if the number of SSBs with quality higher than the threshold is M2, which is greater than M1, then the WTRU can identify the optimal M1 SSBs from the M2 SSBs. The first number of SSBs can also be determined based on UE capabilities. For example, the maximum number of SSBs identified can be limited based on WTRU capabilities (e.g., M3). For example, if the number of SSBs with quality higher than the threshold is M2, which is greater than M3, then the WTRU can identify the optimal M3 SSBs from the M2 SSBs.

[0111] The WTRU can determine time and frequency synchronization based on a first number of SSBs. Based on the determined time and frequency synchronization, the WTRU can decode one or more initial access related signals (e.g., PSS, SSS, PBCH, PBCH-DMRS, SSB index, MIB, and SIB1) for the first number of SSBs. Based on the decoded one or more initial access related signals, the WTRU can receive configurations (e.g., via MIB or SIB1) regarding / indicating whether SSB skipping is enabled at the gNB.

[0112] The gNB can indicate one or more of the following based on one or more of MIB, SIB, RRC, MAC CE, and DCI: whether SSB skipping is enabled; the type of AI / ML model; the number of SSBs in the initial access set A (e.g., the number of planned SSBs, which may include skipped and transmitted SSBs); a list of SSBs in the initial access set A (e.g., a list of planned SSBs, e.g. via ssb-SetA); a list of initial access set B (e.g., a list of transmitted or skipped SSBs for the initial access, e.g. via ssb-SetB); auxiliary information for transmitted or skipped SSBs; the number of transmitted or skipped SSBs; the mode of transmitted SSBs; beam angle related information; and / or associated SSBs.

[0113] In one example, the gNB may indicate one or more of the following based on whether SSB skipping is enabled. For example, a flag (e.g., 1 bit) indication may be supported (e.g., 0 may indicate that SSB skipping is not supported and 1 may indicate that SSB skipping is supported). Based on this indication, the WTRU may determine the operating mode for initial access. For example, if the WTRU receives an indication that SSB skipping is not supported, the WTRU may determine that there is no SSB skipping in the initial access procedure. In one example, if the WTRU receives an indication that SSB skipping is supported, the WTRU may determine that there is an initial access procedure with SSB skipping. The WTRU may determine an indication that the sending WTRU wants to use a skipped SSB for or after the initial access procedure. In one example, this indication may be implicit (e.g., based on the number of SSBs for initial access). For example, if the indicated (or determined) number of SSBs for initial access is less than (or equal to) a threshold (e.g., 32), the WTRU may determine a first operating mode (e.g., no SSB skipping). If the indicated (or determined) number of SSBs for initial access is greater than a threshold, the WTRU can determine a second operating mode (e.g., SSB skipping). In another example, the indication can be implicit (e.g., based on the number of skipped SSBs). For example, if the indicated (or determined) number of skipped SSBs is X (e.g., 0), the WTRU can determine a first operating mode (e.g., no SSB skipping). Otherwise, the WTRU can determine a second operating mode (e.g., SSB skipping). The number of skipped SSBs can be determined as: Number of skipped SSBs = Number of SSBs for initial access – Number of transmitted SSBs.

[0114] In one example, the gNB can indicate one or more of the following based on the type of AI / ML model. The WTRU can receive an indication of the type of AI / ML model for initial access. For example, the WTRU can receive a flag indication having a first value (e.g., value 0) indicating a first type of AI / ML model and a flag indication having a second value (e.g., value 1) indicating a second type of AI / ML model. In another example, a flag indication having a first value (e.g., value 0) can indicate that no AI / ML model is to be used for initial access, a flag indication having a second value (e.g., value 1) can indicate a first type of AI / ML model, a flag indication having a third value (e.g., value 2) can indicate a second type of AI / ML model, a flag indication having a fourth value (e.g., value 3) can indicate a third type of AI / ML model, and so on.

[0115] In one example, the gNB may indicate one or more of the following based on the number of SSBs in the initial access set A (e.g., the planned number of SSBs, which includes skipped and transmitted SSBs, for example). The WTRU may receive an indication of the number of SSBs in the initial access set A. For example, the WTRU may receive an indication (e.g., two bits, where 0 indicates 16 SSBs, 1 indicates 32 SSBs, 2 indicates 64 SSBs, and 3 indicates 128 SSBs). In one example, the WTRU may blindly detect the number of SSBs for the initial access based on the transmitted SSBs. For example, if the number of transmitted SSBs is equal to the number of SSBs in set A, or if the number of transmitted SSBs is a ratio (e.g., half, one-third, one-quarter, etc.) to the number of SSBs in set A.

[0116] In one example, the gNB can indicate one or more of the following based on a list of SSBs in set A for initial access (e.g., a list of planned SSBs, e.g., via ssb-SetA). The WTRU can receive an indication of which SSBs are in set A for initial access. For example, the WTRU can receive a bitmap of the SSBs. If the associated bit in the bitmap of the SSB indicates a first value (e.g., value 0), then the corresponding SSB may not be used for initial access. If the bit indicates a second value (e.g., value 1), then the corresponding SSB may be used for initial access. The indicated payload size can be based on the frequency range of the cell used for operation. For example, if the frequency range is less than (or equal to) X1, the payload size can be F0 bits (e.g., 4). If the frequency range is greater than X1 and less than (or equal to) X2, the payload size can be F1 bits (e.g., 8 bits). If the frequency range is greater than X2, the payload size can be F2 bits (e.g., 64 bits). X1, X2, F0, F1, and F2 can be predefined or semi-statically configured. Indications can be based on existing fields (e.g., in the SIB and / or MIB). For example, the field ssb-PositionsInBurst can be used for this indication. For instance, if the WTRU receives an indication of the operating mode and determines a first mode (e.g., no SSB skip), the WTRU can use ssb-PositionsInBurst for indications of SSBs in the initial access set A.

[0117] In one example, the gNB can indicate one or more of the following based on a list of set B for initial access (e.g., a list of transmitted or skipped SSBs for initial access, e.g., via ssb-SetB). The WTRU can receive an indication of which SSBs were skipped or transmitted. For example, the WTRU can receive a bitmap corresponding to the transmitted or skipped SSBs. If the associated bit of the bitmap with the SSB indicates a first value (e.g., value 0), then the corresponding SSB may not be transmitted. If the bit indicates a second value (e.g., value 1), then the corresponding SSB may be transmitted. The indicated payload size can be based on the frequency range of the cell used for operation. For example, if the frequency range is less than (or equal to) X1, the payload size can be F0 bits (e.g., 4). If the frequency range is greater than X2 and less than (or equal to) X2, the payload size can be F1 bits (e.g., 8 bits). If the frequency range is greater than X2, the payload size can be F2 bits (e.g., 64 bits). X1, X2, F0, F1, and F2 can be predefined or semi-statically configured. Indications can be based on existing fields (e.g., in the SIB and / or MIB). For example, the field ssb-PositionsInBurst can be used for this indication. For instance, if the WTRU receives an indication of an operating mode and determines a second mode (e.g., SSB skipping), the WTRU can use ssb-PositionsInBurst for an indication of set B, which is the emitted or skipped SSB.

[0118] In one example, the gNB may indicate one or more of the following based on auxiliary information for the transmitted or skipped SSB. The WTRU may determine the association between one or more beam IDs and SSBs. The association may be based on beam information configured by the gNB and / or reported by the WTRU. The association may be based on one or more of the following: explicit indication; the order of beam directions; and / or the order of panels and / or TRPs (CORESET group IDs).

[0119] For example, the association between one or more beam IDs and SSBs can be based on explicit indication. The WTRU can receive explicit indication of the beam ID for each SSB (e.g., configuration based on beam information). For example, the WTRU can be configured with one or more beam IDs, and each beam ID can include one or more beam information (e.g., beam direction, beamwidth, panel and / or TRP ID, etc.).

[0120] For example, the association between one or more beam IDs and SSBs can be based on the order of beam directions. Beam IDs can be associated with SSBs based on their direction. For example, a first beam ID can be associated with an SSB having a beam direction with a lowest and / or highest angle (e.g., 5 degrees), and a second beam ID can be associated with an SSB having a second lowest and / or highest angle, and so on.

[0121] For example, the association between one or more beam IDs and SSBs can be based on the order of panels and / or TRPs (CORESET group IDs). Beam IDs can be associated with the order of panels and / or TRPs that include the SSB. For example, a first beam ID can be associated with an SSB having a first panel and / or TRP, and a second beam ID can be associated with an SSB having a second panel and / or TRP, and so on.

[0122] The WTRU can receive an indication of the number of SSBs transmitted or skipped. For example, the WTRU can receive an indication (e.g., a 2-bit indication, such as 0 indicating 8 SSBs, 1 indicating 16 SSBs, 2 indicating 32 SSBs, and 3 indicating 64 SSBs). The payload size of the indication can be determined based on the number of SSBs transmitted or skipped for initial access. For example, if the total number of transmitted or skipped SSBs is less than (or equal to) Y, the payload size can be N1 bits (e.g., 1 bit). If the total number of transmitted or skipped SSBs is greater than Y, the payload size can be N2 bits (e.g., 2 bits). In one example, the WTRU can blindly detect the number of skipped SSBs for initial access based on the number of transmitted SSBs.

[0123] In one example, the number of SSBs transmitted or skipped can be implicitly indicated to the WTRU based on the pattern of the transmitted SSBs. For example, if the pattern is a first pattern, then the WTRU can determine a first number of SSBs transmitted or skipped. If the pattern is a second pattern, then the WTRU can determine a second number of SSBs transmitted or skipped.

[0124] In one example, the number of SSBs transmitted or skipped can be implicitly indicated to the WTRU based on the supported AI / ML model for initial access and / or beam prediction. For example, if the AI / ML model is a first AI / ML model, then the WTRU can determine a first number of SSBs transmitted or skipped. If the AI / ML model is a second AI / ML model, then the WTRU can determine a second number of SSBs transmitted or skipped.

[0125] The WTRU can receive indications of the mode of the transmitted SSBs. For example, the WTRU can receive indications (e.g., 2-bit indications, such as 0 indicating mode #1, 1 indicating mode #2, 2 indicating mode #3, and 3 indicating mode #4). The mode for the indication can be pre-defined or semi-statically configured. The payload size of the indication can be determined based on the total number of planned (set A), transmitted (set B), and / or skipped SSBs. For example, if the total number of SSBs, the number of transmitted, and / or the number skipped are less than (or equal to) Z, the payload size can be N3 bits (e.g., 1 bit). If the total number of planned, transmitted, and / or skipped SSBs is greater than Y, the payload size can be N4 bits (e.g., 2 bits).

[0126] The WTRU may receive one or more of the following information associated with the transmitted and / or skipped SSBs: The WTRU may receive an indication of coverage for each of the initially accessed SSBs (e.g., angular coverage, such as 120 degrees). The WTRU may receive an indication of coverage for the transmitted SSBs (e.g., angular coverage, such as 120 degrees). The WTRU may receive an indication of coverage for the skipped SSBs (e.g., angular coverage, such as 60 degrees). The WTRU may receive an indication of the location, center, and / or orientation of the transmitted SSBs (e.g., 0 degrees). The WTRU may receive an indication of the location, center, and / or orientation of the skipped SSBs (e.g., 0 degrees).

[0127] The WTRU can receive an indication of the granularity of the transmitted SSBs (e.g., 3 degrees). For example, the WTRU can receive a configuration for each of the horizontal and / or vertical domains. For example, the WTRU can indicate a configuration for each of the horizontal and / or vertical domains (e.g., via WTRU capability). For example, the WTRU can receive the granularity of the skipped SSBs (e.g., 12 degrees). For example, the WTRU can receive a configuration for each of the horizontal and / or vertical domains. For example, the WTRU can indicate a configuration for each of the horizontal and / or vertical domains (e.g., via WTRU capability).

[0128] For a given piece of information, the indication can be based on direction (e.g., horizontal angle (or azimuth), vertical angle (or elevation), aiming angle, etc.). For a given piece of information, the indication can be based on WTRU and can be applied to each applicable direction.

[0129] The WTRU can receive configuration information (e.g., via SIB) for at least one of the detected SSB beams. In one example, the information may include a list of candidate skipped SSB beams (ssb-candidate) associated with the corresponding detected SSB beam. In one example, the association may include beams adjacent, neighboring, and / or related to the detected beams from the list of transmitted beams (ssb-SetB). Configuration information about the candidate skipped beams may include beam index, azimuth, elevation, aiming angle, etc. In one example, the WTRU may use the configured list of candidate skipped beams to select downwards and / or determine potential candidates for a prediction of the optimal SSB beam.

[0130] The WTRU can determine which SSB beams are associated with (e.g., adjacent, neighboring, or related) a detected beam (e.g., from ssb-SetB) based on a configured list of candidate SSB beams (e.g., via ssb-candidate in the SIB). For example, a skipped SSB can be associated with an SSB that has an adjacent beam ID (e.g., a skipped SSB with beam ID X can be associated with an SSD with beam ID X+d1 and / or X–d2) or an adjacent order in the list (e.g., the Xth SSB can be associated with the X+d1th SSB and the X-d2th SSB).

[0131] The WTRU can determine k optimal (e.g., predicted) SSB beams based on one or more of the above information (e.g., the highest quality based on RSRP, RSRQ, hypothetical BLER, etc.). For example, the WTRU can use a list of predicted beams along with a list of received candidate SSB beams (e.g., SSB-candidates) to select k optimal SSB beams. The k optimal SSB beams in the list can be sorted against the predicted SSB beams according to an AIML model (e.g., descending order based on RSRP, RSRQ, etc.). The set of predicted SSBs can be sorted in descending order of Reference Signal Received Power (RSRP), and the predicted SSBs are selected from the sorted list.

[0132] Based on the identified k optimal SSB beams, the WTRU can initiate initial access on PRACH resources (e.g., by transmitting a PRACH preamble) (e.g., starting with the SSB beam ranked as the first optimal beam in the list of k optimal SSB beams). When the WTRU uses a PRACH preamble on a PRACH resource corresponding to the predicted SSB, the WTRU can receive, be provided with, and / or be configured with one or more information configurations on one or more SSB-specific (e.g., beam-specific) parameters. The WTRU can receive the configuration as part of the initial access procedure (e.g., via RAR, Msg4, and / or MsgB). As an example, the SSB beam-specific parameters can be information related to the paging search space for the predicted SSB, which the WTRU can receive and index into a list or table indicating the corresponding time and frequency resources. In one example, the gNB determines to transmit the configuration for the WTRU because the gNB can determine, based on the received PRACH, that the WTRU has predicted the predicted SSB because the corresponding SSB was not transmitted first.

[0133] In one embodiment, a PRACH preamble can be transmitted in an AIML scenario with skipped SSBs. In the example solution, the WTRU can perform one or more of the following: The WTRU can be configured with a set of transmitted SSB beams and a set of predicted SSB beams. The WTRU can select the predicted beam for which it performs initial access (e.g., based on the predicted RSRP).

[0134] The WTRU can initiate initial access by transmitting or sending a PRACH or random access preamble on or using a PRACH / random access resource, wherein the PRACH resource can be selected based on one or more of the following: associated detected SSB beams, predicted SSB beams; and / or a combination of multiple detected and / or predicted SSB beams.

[0135] In one example, PRACH resources can be selected based on the associated detected SSB beam. For example, the WTRU can be configured to transmit a random access preamble or a PRACH preamble on a resource corresponding to the associated detected SSB beam or the actually transmitted SSB. The WTRU can indicate the preferred predicted beam to the gNB in ​​accordance with the PRACH preamble selection or Msg3 transmission or in a transmission performed after the RA procedure. The indication sent in the random access message 3 can indicate the skipped SSB. For example, the gNB can indicate whether the predicted beam is accepted (e.g., by sending the same RAPID (preamble ID) or another ID to instruct the WTRU to select another beam (e.g., the detected beam or the predicted beam)).

[0136] For example, this could be beneficial if the gNB does not transmit SSBs due to gNB implementation (e.g., the gNB shuts down those beams for power consumption enhancements). The gNB may also not want to receive anything on those beams. The gNB may choose not to use that beam unless the WTRU requires it.

[0137] In one example, PRACH resources can be selected based on the predicted SSB beams. For instance, the WTRU can be configured to transmit a PRACH preamble on a resource corresponding to one of the predicted SSB beams (e.g., the one with the highest RSRP). The random access preamble or random access resource can indicate the SSBs being skipped. The WTRU can be configured to or determine the use of one or more random access parameters (e.g., for PRACH transmission and RAR reception, such as the number of retransmissions of the PRACH preamble, power ramp rise, etc.)

[0138] In one example, PRACH resources can be selected based on a combination of multiple detected and / or predicted SSB beams. For example, the WTRU can be configured to transmit a PRACH preamble on multiple resources corresponding to the detection and / or prediction of more than one SSB beam (e.g., a first resource may indicate that both the detected SSB and the first predicted SSB beam are preferred beams; a second resource may indicate that both the detected SSB and the second predicted SSB beam are preferred beams, etc.) (e.g., based on the configuration of reception for the detected SSB (e.g., in the direction of the detected SSB)). As an example, if the gNB receives PRACH on a resource corresponding to an SSB beam that is not actually transmitted, the gNB can expect the SSB to be selected based on prediction.

[0139] The WTRU can monitor PDCCH scrambled using RA-RNTI to detect RAR within the periodic RAR window corresponding to the transmitted PRACH and / or the associated detected and / or predicted SSB beam. In one example, if the WTRU receives a RAR or downlink transmission, the WTRU can continue with initial access (e.g., transmission of Msg3, etc.). The WTRU can use the beam associated with the skipped SSB to receive the downlink transmission.

[0140] In this document, Initial Access and Random Access (RA) may be used interchangeably to refer to one or more procedures associated with establishing connectivity between the WTRU and the network. The Random Access procedure may be triggered by multiple events, such as: Initial Access from RRC IDLE; RRC Connection Re-establishment Procedure; DL or UL data arrival during RRC_CONNECTED when the UL synchronization state is “unsynchronized”; UL data arrival during RRC_CONNECTED when no PUCCH resource for a Schedule Request (SR) is available; SR failure; a request made by the RRC during synchronization reconfiguration (e.g., handover); RRC Connection Recovery Procedure from RRC_INACTIVE; Establishment of time alignment for the secondary TAG; Beam failure recovery; and / or Consistent UL LBT failure on the SpCell.

[0141] WTRU can be configured to perform one or more types of initial access, such as: CBRA with 4-step RA; CBRA with 2-step RA; CFRA with 4-step RA; and / or CFRA with 2-step RA.

[0142] In one embodiment, random access resources can be used. The WTRU can receive, identify, or be configured with temporal resource allocations for consecutive random access opportunities (ROs) based on the higher-layer parameter prach-ConfigurationIndex or, if configured, via msgA-PRACH-ConfigurationIndex. These parameters can identify PRACH configuration indexes corresponding to a table that includes random access parameters.

[0143] In one example, one or more of the following parameters can be derived from the table. For example, the preamble format can refer to one of the possible formats: A1, A2, A3, B1, A1 / B1, A2 / B2, A3 / B3, B4, C0, C2. The preamble format can identify the corresponding cyclic prefix (CP) duration, sequence portion duration, and guard duration (if applicable). The frame number and slot number can indicate the frame that can be used for PRACH transmission and the corresponding PRACH slot within the frame. The start symbol can determine the symbol-level index corresponding to the start position of the first RO transmission within the PRACH slot. The number of PRACH slots within a 60 kHz slot can define the number of PRACH slots within a reference PRACH slot; for example, for higher SCS such as 120 kHz, 480 kHz, and 960 kHz, the 60 kHz PRACH slot is considered the reference slot. The number of time-domain PRACH opportunities within a PRACH slot (N) t RA ,slotThe number of consecutive ROs within a PRACH time slot in the time domain can be defined. The PRACH duration can correspond to a preamble format that implies the number of sequence portions within an RO.

[0144] The WTRU can receive frequency domain resource allocations for ROs based on one or more of the following higher-level parameters: msg1-FrequencyStart or msgA-RO-FrequencyStart; and / or msg1-FDM or msgA-RO-FDM. When configured, msg1-FrequencyStart or msgA-RO-FrequencyStart can indicate the offset of the lowest PRACH transmission opportunity in the frequency domain relative to PRB 0. When configured, msg1-FDM or msgA-RO-FDM can indicate the number of PRACH transmission opportunities for FDMs in a time-domain RO. For example, the WTRU can receive, identify, or be configured with the number (M) of ROs in the frequency domain for each time-domain PRACH opportunity based on the higher-level parameters msg1-FDM, msg1-FDM-16, or msgA-RO-FDM, where, when configured, msg1-FDM = {1, 2, 4, 8}. For example, the WTRU can number the PRACH frequency resources starting from the lowest frequency, in ascending order of the initial uplink BWP during initial access, or otherwise in ascending order of the active uplink BWP, n RA ={0, 1, …, M-1}.

[0145] The WTRU can receive the association and mapping between SS / PBCH block indices and PRACH transmission timings based on the higher-layer parameter ssb-perRACH-OccasionAndCB-PreamblesPerSSB = {1 / 8, 1 / 4, 1 / 2, 1, 2, 4, 8, 16}. In addition to the number of preambles per SS / PBCH block index per PRACH timing, the parameter can also indicate the number of SS / PBCH block indices associated with the PRACH transmission timing. The WTRU can perform PRACH transmissions in the corresponding random access resources and according to the spatial relationship with the associated SS / PBCH blocks.

[0146] In example embodiments, contention-based PRACH preambles and / or contention-free PRACH preambles can be used. In one example, the same set of preambles as described above can be configured for each SSB, allowing multiple WTRUs to have access to the same preamble, thus making the initial access procedure similar to a contention-based scenario. In one example, these preambles can refer to conventional preambles that convey information related to the SSB beam (detected, skipped, and / or predicted SSBs) selected by the WTRU. In one example, these preambles can convey additional information, implicitly or explicitly as described above. In cases where a preamble is selected by more than one WTRU, the WTRU can receive from the network (e.g., in a RAR message or in Msg4 or MsgB) an indication that a preamble has been acquired or another preamble has been selected. The WTRU can interpret the absence of a preamble ID received in a response from the network (e.g., in Msg4 or MsgB) within a pre-configured time window as an indication that the preamble has been acquired by another WTRU. The WTRU can then select another preamble in a manner similar to contention-based initial access. If contention resolution is unsuccessful after one or more Msg 3 transmissions (retransmissions), the WTRU can revert to Msg 1 transmission. In the absence of contention, the WTRU can receive an acknowledgment from the network (in RAR, Msg 4, or MsgB) that the preamble has been accepted, for example, by receiving the same random access preamble ID (RAPID). The WTRU can then use the UL authorization scheduled in the response to transmit Msg 3.

[0147] In one example, a preamble can be a dedicated preamble specified by the network in a contention-free manner. For example, one or more preambles can be "reserved" by the network for a WTRU or a group of WTRUs. Contention-free preambles can correspond to the same or different sets of resources as contention-based preambles (e.g., RACH timings in the time domain, PRACH timings in the frequency domain, SSBs corresponding to one or more beams in the spatial domain). These preambles can correspond to any transmitted, skipped, or predicted SSB.

[0148] The MsgA (Message Access Assist) in a two-step initial access procedure can include a contention-free preamble on the PRACH and a payload on the PUSCH. After the MsgA transmission, the WTRU can monitor responses from the network within a pre-configured window. Also in this case, the PRACH preamble used by the WTRU can correspond to the transmitted / associated or predicted SSB (Service Subsystem for Broadband). Dedicated preamble and PUSCH resources are configured for the MsgA transmission, and the WTRU terminates the initial access procedure upon receiving a network response.

[0149] In this embodiment, PRACH resources can be selected for the predicted beam. The WTRU can detect the first SSB beam (e.g., during initial access). The WTRU can predict and / or determine one or more predicted SSBs from a list of untransmitted skipped SSB beams or preferred predicted SSBs (e.g., based on an AIML system). The WTRU can select the optimal predicted SSB and initiate the initial access procedure accordingly (e.g., PRACH preamble transmission).

[0150] In one example, (e.g., alternatively) the WTRU can be configured (e.g., by the network) to have information relating to the associations between two or more SSB beams. For example, the WTRU can receive a mapping table from the network that indicates the associations between two or more transmitted and / or skipped SSB beams based on spatial correlation (e.g., neighboring or adjacent beams) or beam parameters (e.g., two beams at a specific elevation angle or with an RSRP above a threshold can be associated).

[0151] In one example, the association between one or more transmitted and / or skipped SSBs can be configured by the network and indicated to the WTRU according to the beam index. In one example, the association can be applied under one or more conditions. For example, the WTRU can be configured to apply the association if one or more conditions are met (e.g., if at the cell edge, use the association; otherwise, use the detected beam (e.g., conventional)).

[0152] The WTRU can determine PRACH resources for transmissions of the selected, configured, and / or determined PRACH preamble. One or more of the following may be applicable: PRACH resources for a detected SSB based on the detected SSB beam; PRACH resources for a predicted SSB based on the associated detected SSB beam; PRACH resources for a predicted SSB based on the predicted SSB beam; and / or PRACH resources based on a combination of multiple detected and / or predicted SSB beams.

[0153] The WTRU can select PRACH resources based on the detected SSB beams for initial access (e.g., when the WTRU performs initial access for the first time upon joining a new cell or when the WTRU performs initial access after a long period of inactivity). During a session, the WTRU can receive (e.g., from the gNB) configurations for using associated detected and / or predicted SSB beams, such that for future instances of initial access, the WTRU can select PRACH resources based on either the associated detected or predicted SSB beams.

[0154] In one embodiment, the WTRU may determine or be configured to perform a PRACH preamble transmission based on the PRACH resources corresponding to the associated detected SSB beam. The WTRU may indicate a preferred predicted SSB beam (e.g., to the gNB) based on the WTRU selection of the PRACH preamble. In one example, if the WTRU has predicted the best predicted beam as a first (e.g., associated and / or candidate) skipped beam, the WTRU may select and transmit a PRACH preamble from a first set of preambles; if the WTRU has predicted the best predicted beam as a second (e.g., associated and / or candidate) skipped beam, the WTRU may select and transmit a PRACH preamble from a second set of preambles; and so on. In one example, (e.g., alternatively) the WTRU may indicate a preferred predicted SSB beam (e.g., to the gNB) as part of initial access signaling (e.g., Msg3 and / or MsgB transmission). The WTRU may (or otherwise) indicate the preferred predicted SSB beam (e.g., to the gNB) after switching to connected mode and after connecting to the gNB.

[0155] Transmitting a PRACH preamble on the resource corresponding to the detected SSB can be useful if the network is not transmitting an SSB due to gNB implementation. For example, the gNB may shut down some beams for power consumption enhancements. The gNB may not want to receive any preambles corresponding to these beams or any data transmissions via these beams. A beam may not be activated unless or until the WTRU specifically requests it (e.g., via selecting and transmitting a preamble corresponding to a preferred predicted beam). The network may not activate a beam despite a request from the WTRU. For example, the gNB may decide not to activate the WTRU's preferred predicted beam because there may be already activated (e.g., adjacent and / or neighboring) SSBs that the gNB determines are sufficient to satisfy the WTRU's data transmission requirements. In this case, the gNB may send an instruction to the WTRU to select the corresponding SSB beam.

[0156] In this document, the preamble and the PRACH preamble can be used interchangeably. In one embodiment, the WTRU can be configured to transmit one or more associated preambles for one or more SSBs. For example, the WTRU can indicate selected, predicted, skipped, and / or detected SSBs (e.g., indexes) based on the selection of the PRACH preamble. For example, a first preamble can be used to indicate a first selected SSB (e.g., from a list of skipped SSBs and / or from a list of transmitted SSBs, from a list of predicted SSBs, etc.); a second preamble can be used to indicate a second selected SSB, and so on.

[0157] A preamble can be a long-sequence preamble or a short-sequence preamble. A preamble can be a traditional preamble or a new preamble. In a new preamble, additional bits can be added to convey additional information, for example. The preamble format selected by the WTRU can depend on the additional information and / or scenario that the WTRU may want to indicate (e.g., to the network). For example, in the case of cell deployment, some preamble formats may be used for large cells, while others may be used for small cells, macrocells, etc. For example, in the case of frequency range, some preamble formats may be used in FR1 deployment, and others may be used in FR2 deployment. In the case of subcarrier spacing, for example, a first preamble format may be used for a first subcarrier spacing (e.g., 15 or 30 kHz), a second preamble format may be used for a second subcarrier spacing (e.g., 60 or 120 kHz), and so on. In cases where there is specific information for AI / ML beam management, for example, the WTRU may use a first preamble for a first detected SSB, a second preamble for a predicted SSB based on a first associated skipped SSB, a third preamble for a predicted SSB based on a second associated skipped SSB, and so on.

[0158] The WTRU can use selected preambles to indicate (e.g., to the network) the selected and / or preferred SSBs chosen by the WTRU. In one example, the WTRU can implicitly indicate additional information based on the selection of the PRACH preamble. For example, the WTRU can determine or be configured to use a first set of preambles for a first operating mode, a second set of preambles for a second operating mode, and so on. For example, the WTRU can select a first preamble for a first SSB to indicate that the AI / ML model at the WTRU is using a set of B beams of a first type, size, etc. for beam prediction; the WTRU can select a second preamble for the first SSB to indicate that the AI / ML model at the WTRU is using a set of B beams of a second type, size, etc. for beam prediction, and so on. In one example, the WTRU can select a first preamble for the first SSB to indicate that a first type of AI / ML model (e.g., a recurrent neural network (RNN)) is used by the WTRU; the WTRU can select a second preamble for the first SSB to indicate that a second type of AI / ML model (e.g., a deep neural network (DNN)) is used at the WTRU, and so on. In the example, additional bits can be added to the preamble to convey and / or indicate additional information. In many more examples, the additional information can be encoded using the preamble (e.g., through scrambling).

[0159] In one example, an AI / ML-enabled WTRU can predict the optimal beam for a future timeframe based on parameters such as historical beam IDs and their corresponding RSRPs, beam angles, associated beams, etc., for example, the beam with the highest predicted RSRP. The WTRU can be configured to transmit a PRACH preamble on the resource corresponding to one of the (e.g., the optimal) predicted SSB beams (e.g., the one with the highest predicted RSRP based on the output of the AI / ML model).

[0160] In one example, the WTRU may receive configuration information relating to how to generate a preamble corresponding to a predicted beam in an SIB (e.g., an existing SIB or an AI / ML-specific SIB). In one example, the WTRU may be configured with a space (e.g., an ID space) by the network, where the WTRU may be able to generate a preamble corresponding to the predicted SSB beam. If the gNB receives a PRACH on a resource corresponding to an SSB beam that is not actually transmitted, the gNB may expect to be able to select, predict, and / or determine the SSB based on the prediction.

[0161] In one example, the WTRU might be able to use the same preamble associated with the current beam at a future time. For instance, if the WTRU performs initial access at time T1 using the detected / transmitted beam (e.g., beam X) to transition to a connected state, the WTRU can then proceed to an idle state at time T2. At time T3, the WTRU can determine, based on the predicted beam, to perform initial access at a later time T4. If the WTRU has already remained stationary, the AI / ML model can determine the same beam X as the most suitable beam for the WTRU to use for initial access. Thus, the WTRU can use the same preamble it previously used to perform initial access.

[0162] In one embodiment, a WTRU transmitting a PRACH preamble on a PRACH resource based on a predicted SSB beam can be configured or determined to use one or more different random access parameters compared to a (conventional) PRACH preamble transmission on the resource based on a detected SSB. In one example, the WTRU can be explicitly configured with random access parameter values. In another example, the WTRU can receive differential values ​​and / or offsets of the configured parameters to be applied to a (conventional) PRACH preamble transmission on the resource based on the detected SSB. As an example, the number of retransmissions, power ramp rise, random access response time window, etc., of the PRACH preamble can differ from a (conventional) PRACH preamble transmission on a PRACH resource based on a predicted SSB beam.

[0163] In one example, when the WTRU is configured to perform initial access using a predicted SSB, the RACH resources, configurations, and / or parameters associated with one or more predicted SSB beams can be configured to remain active for a longer duration. Those RACH resources and / or configurations can include any of the preamble, sequence, partition, time, and / or frequency resources associated with the RACH. RACH resources can also include the RACH timing that the WTRU can use when transmitting the RACH preamble. Parameters associated with RACH resources can include start / stop time, transmission duration, periodicity, Tx power, Tx spatial direction, etc. For example, the RACH resources can be selected by the WTRU from a set that is common to multiple UEs or dedicated to the WTRU. For example, common or dedicated RACH resources can be accessed via a broadcast channel / beam (e.g., SIB, SSB), via an initial access message (e.g., in Msg 2 or Msg B), or (pre)configured in the WTRU.

[0164] In one embodiment, the WTRU can be configured to transmit a PRACH preamble on multiple resources corresponding to the detection and / or prediction of more than one SSB beam. In one example, the WTRU can use (combined) PRACH resources to indicate that, in addition to the detected SSB (e.g., having the highest measured and / or predicted RSRP), the WTRU also prefers a predicted SSB. The WTRU can use spatial filters and / or beam directions corresponding to the detected SSB and / or the QCL of the detected SSB for PRACH transmission. For example, the WTRU can use a first (combined) set of PRACH resources to indicate that the detected SSB and a first predicted (and / or skipped) SSB beam are preferred beams; the WTRU can use a second (combined) set of PRACH resources to indicate that the detected SSB and a second predicted (and / or skipped) SSB beam are preferred beams, and so on.

[0165] The network can determine the optimal SSB beam for authorizing the WTRU for initial access, for example, based on load, beam quality (e.g., RSRP), etc. The network can indicate its selected beam by using a preamble ID (RAPID) corresponding to that beam (e.g., in a RAR message). After the transmission of the PRACH preamble on the (combined) PRACH resources, the WTRU can monitor the downlink control channel (e.g., CORESET, PDCCH, etc.) corresponding to each corresponding preferred SSB (e.g., the detected SSB and the first predicted SSB, the detected SSB and the second predicted SSB, etc.). In one example, the WTRU can detect one or more RAR messages (e.g., RAR PDCCH), where the WTRU can determine the corresponding SSB based on the received RAPID in the RAR message. Any or more of the solutions described above for initial access based on the detected or predicted beams can also be applied in this case.

[0166] Following the transmission of a PRACH preamble on a detected, skipped, and / or predicted beam, the WTRU can monitor the PDCCH scrambled using RA-RNTI to detect a RAR within the periodic RAR window corresponding to the transmitted PRACH and / or the associated detected and / or predicted SSB beam. Upon receiving a RAR (in Msg 2 / Msg B), the WTRU can also receive a UL authorization included in the RAR, which can be used to transmit an RRC establishment request (e.g., Msg 3). The network can estimate timing (e.g., propagation delay) based on the received preamble (e.g., in Msg 1 / Msg A) and can send a TA value to the WTRU in the RAR message. In response to Msg 3, the WTRU can receive an RRC establishment complete message (e.g., Msg 4), which, if successful, can transition the WTRU to a connected state. In one embodiment, if the PRACH preamble transmission based on the predicted SSB beam fails (e.g., RAR is not received within the RAR window period), the WTRU can determine the backoff procedure.

[0167] The WTRU may exhibit certain behaviors in the event of a failed PRACH transmission. In one embodiment, the WTRU may perform one or more of the following: The WTRU may be configured with a set of transmitted SSB beams and a set of predicted SSB beams. The WTRU may select a predicted beam (e.g., based on a predicted RSRP) for which it performs initial access (e.g., a PRACH preamble transmission). The WTRU may monitor PDCCHs scrambled using RA-RNTI to detect RAR within a periodic RAR window corresponding to the transmitted PRACH and / or the associated detected and / or predicted SSB beams. If the WTRU receives a RAR, it may continue with initial access (e.g., a transmission of Msg3, etc.). If the WTRU does not receive a RAR within the configured time window or based on a counter, the WTRU may perform one or more of the following example methods. In one example method, the WTRU can switch the SSB beam to another SSB beam from a list of predicted SSB beams, and so on up to k beams (e.g., selected in descending order of RSRP). The set of predicted SSBs can be sorted in descending order of Reference Signal Received Power (RSRP), and a predicted SSB can be selected from the sorted list. In one example method, the WTRU can transmit a PRACH for the detected beam. In one example method, the WTRU can wait for a conventional SSB burst for each transmitted SSB beam. For example, the gNB can have an SSB burst for each expected SSB beam (ssb-SetA) that may be transmitted using a longer period. For example, after M SSB bursts for skipped SSB beams, the gNB can transmit an SSB burst for each expected beam transmitted. The WTRU can wait for the maximum duration of M SSB bursts (e.g., M is configured in MIB or SIB1), and can then detect the optimal SSB beam accordingly. In one example approach, the WTRU can reject the cell and attempt to detect another SSB block or another cell in a different synchronization grating.

[0168] The WTRU can be configured with a set of transmitted SSB beams and a set of predicted SSB beams. In one or more example embodiments herein, the transmitted SSB beams may be associated with set B or a configuration thereof. In one example embodiment, the WTRU may be configured to predict the RSRP of a first beam (e.g., the predicted beam) based on the measured RSRP of a second beam (e.g., the transmitted beam). The terms predicted beam and skipped beam may be used interchangeably. The terms transmitted beam, set B beam, and measured beam may be used interchangeably. The term beam may refer to an SSB beam, a CSI-RS beam, or both.

[0169] In one example embodiment, the WTRU can be configured with parameters for the random access procedure corresponding to the skipped beam, wherein one or more of these parameters can be specifically configured for the preamble transmissions associated with the predicted beam. For example, the WTRU can be configured with a maximum number of random access preamble transmissions associated with each predicted beam and / or configured jointly for each predicted beam. Possibly different values ​​for the maximum number of retransmissions can be configured for the predicted beam and the detected beam. Possibly different values ​​for the ra-ResponseWindow (ra-response window) can be configured for the predicted beam and the detected beam.

[0170] In one embodiment, a preamble transmission (RA) associated with the skipped SSB can be performed. The WTRU can be configured to predict one or more parameters (e.g., RSRP) of one or more SSB beams (e.g., predicted SSB beams) based on one or more parameters (e.g., RSRP) of one or more of the measured SSB beams (e.g., transmitted SSB beams). The WTRU can be configured to select the optimal beam for the preamble transmission, where the optimal beam can be the predicted beam or the detected beam. In a first solution, if the difference between one or more predicted parameters and one or more measured parameters (e.g., RSRP) is higher than a (pre)configured threshold, the WTRU can select the detected beam for the PRACH preamble transmission. Otherwise, the WTRU can select the predicted beam for the PRACH preamble transmission. The WTRU can determine the parameters to be applied for the random access procedure based on the type of beam, where the type of beam can refer to transmitted SSB beams, predicted SSB beams, etc.

[0171] In one example embodiment, the WTRU can be configured with a first ra-ResponseWindow (e.g., a random access response time window) value and a second ra-ResponseWindow value. If the preamble transmission is associated with a detected SSB beam, the WTRU can apply the first ra-ResponseWindow value. If the preamble transmission is associated with a predicted SSB beam, the WTRU can apply the second ra-ResponseWindow value. The WTRU can be configured with different sets of retransmission counts and power ramp parameters based on the type of beam selected for the random access procedure. During preamble transmission, the WTRU can monitor the PDCCH scrambled using RA-RNTI to detect a Retransmission Arrival (RAR) within the ra-ResponseWindow corresponding to the transmitted PRACH and / or the associated detected and / or predicted SSB beam. If the WTRU receives a RAR, it can proceed with initial access (e.g., transmission of Msg3, etc.).

[0172] The WTRU may exhibit certain behavior in the event of a failed preamble transmission on a predicted beam. In one example embodiment, the WTRU may be configured to handle a failed preamble transmission according to the type of beam associated with the preamble transmission. Here, beam type may refer to the transmission state of the beam (e.g., transmitted and / or measured beam, not transmitted (e.g., predicted beam), etc.). For example, when transmitting a preamble associated with a predicted beam, if the WTRU does not receive a random access response (RAR) before the ra-ResponseWindow expires, the WTRU may consider the RAR reception unsuccessful (e.g., RAR failure associated with the predicted beam). In one example embodiment, the WTRU may be configured to maintain a preamble transmission counter specific to the preamble transmission associated with the predicted beam or the predicted SSB. In one example embodiment, the WTRU may be configured to increment the counter associated with the predicted beam upon unsuccessful RAR reception.

[0173] The WTRU can exhibit a behavior based on a specific maximum transmittance for a predicted beam. When the RAR associated with the predicted beam fails, the WTRU can be configured to perform a preamble retransmission on that predicted beam. The WTRU can be configured to perform retransmissions on the same predicted beam up to the maximum number of retransmissions. In one example embodiment, the maximum number of retransmissions can be configured specifically for each predicted beam. In one example, the maximum number of retransmissions can be configured to be greater than or equal to 1. When the maximum number of retransmissions is reached on a specific predicted beam, the WTRU can be configured to switch to the next best predicted beam. For example, the next best predicted beam can be determined based on descending RSRP. The set of predicted SSBs can be sorted in descending order of Reference Signal Received Power (RSRP), and a predicted SSB can be selected from the sorted list. In one example embodiment, when the maximum number of retransmissions is reached on a specific predicted beam, the WTRU can be configured to switch to the next best detected beam. In one example embodiment, when the maximum number of retransmissions is reached on a specific predicted beam, the WTRU can be configured to switch to the next best beam, regardless of whether that beam is the predicted or measured beam.

[0174] The WTRU can exhibit a behavior based on the cumulative maximum retransmission count across all predicted beams. In one example embodiment, the WTRU can be configured with a first maximum retransmission count and a second maximum retransmission count, wherein the first maximum retransmission count can be associated with each predicted beam, and the second maximum retransmission count can be associated with the cumulative retransmission attempts across each predicted beam. The first maximum retransmission count value can be less than or equal to the second maximum retransmission count. In one example embodiment, upon reaching the second maximum retransmission count, the WTRU can be configured to switch to the next best detected beam. In one example embodiment, the WTRU can be configured to switch a maximum number of predicted beams during a random access procedure. The maximum number of predicted beams can be pre-configured herein. Upon switching the maximum number of predicted beams, the WTRU can be configured to switch to the next detected beam. In one example embodiment, the WTRU can be configured with a maximum retransmission count across multiple (e.g., each) predicted beams.

[0175] In one embodiment, the WTRU can determine specific retransmissions for the predicted beam based on a confidence level. The WTRU can be configured with (pre)configured rules to determine the maximum number of retransmissions for each predicted beam. For example, considering the maximum number of retransmissions across each predicted beam, the WTRU can determine the maximum number of retransmission attempts for each predicted beam based on the prediction confidence level. For example, the WTRU can retransmit N1 times on a first predicted beam with confidence level C1 and N2 times on a second beam with confidence level C2, where N1 > N2 if C1 > C2.

[0176] The WTRU can wait for conventional SSB bursts for all transmitted SSB beams. In an example embodiment, if the number of RAR failures associated with one or more of the predicted beams exceeds a pre-configured number, the WTRU can be configured to perform a random access procedure based on conventional SSB bursts for each transmitted SSB beam. Herein, a RAR failure can be triggered based on one or more of the following conditions: when the maximum retransmission associated with the predicted beam is exceeded, when the maximum cumulative retransmission associated with each predicted beam is exceeded, when the maximum number of retransmissions on the predicted beams is exceeded, etc. The WTRU can be configured to suspend the ongoing random access procedure and wait for the transmission of a conventional SSB burst. For example, the WTRU can be configured with conventional SSB beams via ssb-PositionsInBurst configuration (e.g., in SIB1). The WTRU can be configured with a longer period for the conventional SSB beams and a shorter period for SSB bursts for the set of B beams. For example, after M SSB bursts with respect to the skipped SSB beam, the WTRU can be configured to receive SSB bursts with respect to the conventional SSB beam. The WTRU can be configured with a value based on M in MIB or SIB1. For example, in the event of a RAR failure associated with the predicted beam, the WTRU can be configured to perform a random access procedure based on the reception of the conventional SSB beam.

[0177] The WTRU can reject a cell and trigger initial access on a different cell. In one example embodiment, when a RAR associated with one or more predicted beams fails more than a pre-configured number of times, the WTRU can be configured to perform one or more of the following actions: For example, the WTRU can abort an ongoing random access procedure. The WTRU can indicate a random access problem to a higher layer. Based on the determination that a RAR was not successfully received during the random access response window and that the number of retransmissions for a first predicted SSB or a second predicted SSB exceeds the maximum number of retransmissions, the WTRU can be further configured to indicate a random access problem to a higher layer. The WTRU can prohibit initial access in the cell for a configured amount of time (e.g., until a (pre)configured timer expires). The WTRU can trigger initial access on a different cell. (For example, the WTRU might attempt to detect SSB blocks in the cell on the same frequency (within the frequency range) or different frequencies (between frequencies), different synchronization gratings, etc.)

[0178] In an embodiment, a correction and acknowledgment process can be performed for a predicted beam based on the received RAR. In this embodiment, the terms "skipped SSB" and "beam not actually transmitted" are used interchangeably. In an example embodiment, the WTRU can perform one or more of the following: The WTRU can determine or select the predicted SSB beam as the optimal beam (e.g., based on the predicted RSRP) based on the detected and / or received SSB beams and an AIML model. The detected SSB beam is an actually transmitted SSB, and the predicted SSB beam is an SSB not currently transmitted by the base station. The WTRU receives indications of both the actually transmitted SSB and the predicted SSB. The WTRU can initiate an initial access procedure by sending a PRACH preamble for the predicted SSB beam (e.g., in time and frequency resources associated with the predicted SSB beam) or by transmitting a random access preamble using random access resources. The random access preamble or random access resources are associated with the predicted SSB. WTRU can monitor and receive RARs in the RAR window.

[0179] After receiving a RAR (e.g., a RAR PDCCH and / or RARPDSCH on the beam of the predicted SSB beam QCL), the WTRU can measure the RSRP (e.g., based on a reference signal, such as DMRS, in the RAR message). The RAR can be received via the beam associated with the predicted SSB. The measured RSRP can be associated with the received RAR. The WTRU can compare the measured RSRP based on the received RAR with the predicted RSRP for the predicted SSB, or determine the difference between the predicted RSRP for the predicted SSB and the measured RSRP for the predicted SSB. The predicted SSB is based on the predicted RSRP for the predicted SSB. The WTRU can be configured with or receive (e.g., via MIB, SIB1, and / or RAR) one or more parameters related to an offset and / or threshold for comparing the RSRP measured based on the RAR (e.g., PDCCH DMRS or PDSCH DMRS) with the RSRP predicted for the SSB. For example, the RSRP measured from the SSB and DMRS can be different. Furthermore, the transmit power for the SSB and DMRS can have (e.g., large) differences. Therefore, the gNB can provide an offset / threshold (e.g., 10 dB) for comparison. The WTRU can verify the accuracy of the prediction based on the comparison and one or more of the offset or threshold (e.g., determining whether the difference between the predicted RSRP and the measured RSRP is below a threshold (e.g., 10 dB)). If the difference between the predicted RSRP and the measured RSRP is below or less than the (pre)configured threshold, the WTRU can determine that the predicted beam is sufficiently accurate and can continue transmitting further signals (e.g., Msg3) using the predicted beam by sending an indication requesting continued use of the beam associated with the predicted SSB for subsequent communication. If the difference between the predicted RSRP and the measured RSRP is above or greater than the (pre)configured threshold, the WTRU can determine that the predicted beam is not sufficiently accurate. The WTRU can reject the predicted beam and can continue to select another beam or follow the procedures considered for the failed PRACH transmission by transmitting a new predicted SSB, and perform a new initial access procedure associated with the beam corresponding to the new predicted SSB. In one example, (e.g., alternatively), if the WTRU has already transmitted a PRACH based on a combination of multiple (e.g., two) detected and / or predicted SSB beams, the WTRU can receive multiple (e.g., two) RAR messages for the corresponding beams. The WTRU can measure the RSRP for each of the received RAR messages and can determine the optimal beam (e.g., one with a higher RSRP). The WTRU can transmit further signals (e.g., Msg 3) based on the selected optimal beam.

[0180] The WTRU can detect one or more SS / PBCH blocks (SSBs) from one or more cells (e.g., during initial access, cell search, and / or cell selection (reselection)), where the cells can be candidate cells for initial access and / or cell selection (reselection). The WTRU can determine, indicate, and / or select at least one of the detected SSBs from at least one of the detected and / or candidate cells as the optimal SSB (e.g., having the highest measured and / or calculated received power (e.g., RSRP), the lowest measured and / or calculated interference, etc.). In one example, the WTRU can detect, decode, and receive one or more information parameters (e.g., via MIB or SIB1) relating to whether a skipped SSB is enabled in a detected cell. In one example, the WTRU can receive one or more information parameters relating to a list of planned SSBs set A (e.g., ssb-SetA), a list of transmitted SSBs (e.g., ssb-SetA), and / or a list of skipped or untransmitted SSBs.

[0181] In one example, the WTRU can be configured with or determine a first type of SSB beam (e.g., a transmitted SSB beam), a second type of SSB beam (e.g., a predicted SSB beam), and so on. The WTRU can detect one or more transmitted SSB beams and measure beam quality (e.g., RSRP). The WTRU can use the measured beam quality for the detected transmitted SSB beams to predict the beam quality (e.g., the predicted RSRP) of the predicted SSB beams (e.g., by using an AI / ML model). The WTRU can use SSB beams from different types (transmitted, predicted, etc.) to perform initial access, cell selection (reselection), and so on. For example, the WTRU can select one or more SSB beams based on the beam quality for initial access (e.g., the beam with the highest RSRP). The WTRU can use the measured beam quality (e.g., RSRP) of the received SSB beams and / or the predicted beam quality (e.g., the predicted RSRP) of the predicted SSB beams.

[0182] In one example, the WTRU can determine to send a PRACH preamble to the detected cell, where the WTRU can determine the time and frequency resources for transmitting the PRACH in association with the predicted SSB beam. After the PRACH preamble is transmitted, the WTRU can monitor and attempt to detect RAR messages (e.g., DCIs with CRCs scrambled using RA-RNTI) within a period of the Random Access Response (RAR) window or boundary. In one example, if the WTRU determines to use a 4-step Random Access (RA) procedure, the WTRU can transmit the configured, selected, and / or determined PRACH preamble to the cell. After transmitting the PRACH preamble, the WTRU can monitor DL ​​messages (e.g., PDCCH and / or PDSCH) that provide UL authorization (e.g., indication RAR messages). The WTRU can transmit UL messages or indications (e.g., in a PUSCH) based on the UL authorization. In one example, if the WTRU determines that a two-step RA is to be used, the WTRU may transmit a MsgA, which may include a configured, selected, and / or determined PRACH preamble, and a PUSCH carrying the message, to the cell. After transmitting the MsgA, the WTRU may monitor DL ​​messages (e.g., PDCCH) that may include (e.g., at least) RAR and may include contention resolution information (e.g., indicating MsgB).

[0183] A WTRU (e.g., a UE with AIML capability) can select the cell to camp on (e.g., as a suitable cell) (e.g., during the initial access and / or cell selection (reselection) process). In one example, the WTRU can select a cell based on one or more measured parameters (e.g., measured, evaluated, and / or predicted RSRP, RSRQ), cell ranking configuration, measured and / or evaluated interference, etc. The WTRU can select a predicted SSB (e.g., SSB beam) as the best SSB in the cell. The WTRU can transmit a PRACH preamble to the selected cell, which is associated with the selected predicted SSB. The WTRU can indicate its determined or selected active operating mode (e.g., AIML operation) by, for example, transmitting a PRACH (e.g., by transmitting a PRACH on AIML RO time and frequency resources and / or by using a PRACH preamble selected from a first set indicating that the WTRU supports AIML, such as as described herein).

[0184] Beam quality parameters can be measured based on one or more received RAR messages. In an example embodiment, the WTRU (e.g., which has already transmitted a PRACH preamble based on a predicted SSB) can measure one or more beam quality parameters (e.g., probabilities of RSRP, RSRQ, SINR, LOS, etc.) based on one or more reference signals received in the RAR message (e.g., via a beam with a selected predicted SSB beam QCL). In one example, the WTRU can determine the measured parameters or be configured to compare the measured parameters with corresponding predicted parameters. The WTRU may need to (re)evaluate the measured parameters to scale them so that the WTRU can compare the measured parameters with the predicted parameters. The WTRU can receive, determine, be provided with, or be (pre)configured (e.g., via MIB, SIB, etc.) one or more scaling rules and / or parameters (e.g., offset values, scaling values, thresholds, etc.).

[0185] The (re)evaluation and / or scaling of the measured parameters can be useful because, for example, RSRP measured from SSB and DMRS can be in different scalings, such as due to different frequency BWP and / or ranges of RS in SSB and DMRS, different transmit powers for SSB and DMRS, etc. The WTRU can be determined or configured to use one or more scaling rules (e.g., adding, subtracting, multiplying, or dividing one or more scaling values) to enable comparison of values. One or more of the following may be applicable: RSRP, RSSI, RSRQ; SINR; probability of LOS; etc. For example, when RSRP, RSSI, and RSRQ are applicable, the WTRU can receive one or more scaling rules and scaling parameters to add, subtract, multiply, divide, etc., with respect to the corresponding measured parameters (e.g., including received signal power, received signal strength, etc.). For example, when SINR is applicable, the WTRU can receive one or more scaling rules and scaling parameters to add, subtract, multiply, divide, etc., with respect to the measured SINR parameters (e.g., including received signal power, received interference power, received signal strength, received interference strength, etc.). For example, when the probability of LOS is applicable, the WTRU can receive one or more scaling rules to be applied (e.g., addition, subtraction, multiplication, division) to the measured probability of LOS for the received RS, along with the RAR PDCCH and / or PDSCH signals.

[0186] Additional parameters may exist, which may include the beam quality (e.g., RSRP) estimated using RS associated with the RAR and the offset between the beam and the SSB beam. For example, after receiving a RAR (e.g., RAR PDCCH and / or RAR PDSCH on the beam associated with the selected predicted SSB beam QCL), the WTRU can estimate the RSRP of the selected predicted SSB beam by measuring the beam RSRP of one or more RSs in the RAR message (e.g., DMRS of the RAR PDCCH and / or RSR PDSCH) and adding the offset configured or indicated by the gNB.

[0187] The accuracy of the prediction can be verified based on one or more RAR messages. In one embodiment, the WTRU can determine and / or verify the accuracy of the prediction based on a comparison of the measured parameters from the RAR with the predicted parameters for the predicted SSB, along with one or more offset values ​​and / or thresholds. The WTRU can receive, determine, be provided with, and / or be (pre)configured (e.g., via MIB, SIB, etc.) one or more thresholds to compare the measured parameters with the corresponding predicted parameters. In one example, the WTRU can determine that the difference between one or more of the predicted parameters and the corresponding re-evaluated and / or expanded parameters based on the measured parameters from RAR messages (e.g., PDCCH and / or PDSCH) is less than the corresponding threshold. The WTRU can determine that the accuracy level for the predicted SSB is acceptable and can determine to continue the initial access procedure (e.g., transmission of Msg3).

[0188] In one example, (e.g., otherwise) the WTRU may determine that the difference between one or more of the predicted parameters and the corresponding (re)evaluated and / or expanded parameters based on measured parameters from RAR messages (e.g., PDCCH and / or PDSCH) exceeds a corresponding threshold. The WTRU may determine that the accuracy level for the predicted SSB is unacceptable. One or more of the following may apply: the WTRU that has determined that the first predicted SSB beam may not meet the required accuracy may choose to use the second predicted SSB beam for the initial access procedure; the WTRU may follow the procedure considered for a failed PRACH transmission; and / or the WTRU may continue the initial access procedure (e.g., via Msg3 transmission), and / or connect to the cell based on a beam with the same spatial relationship as the predicted beam (e.g., with the predicted beam QCL).

[0189] In one example, a WTRU that has determined that a first predicted SSB beam may not meet the required accuracy may choose to use a second predicted SSB beam for the initial access procedure. The WTRU may stop and / or reject an ongoing initial access procedure based on the first predicted beam. The WTRU may initiate a new initial access procedure based on the second predicted beam. The WTRU may select the second predicted beam based on a list of k best predicted SSB beams (e.g., sorted by the highest quality based on RSRP, RSRQ, hypothetical BLER, etc.). Based on the determined second best predicted SSB beam, the WTRU may initiate initial access on the PRACH resource corresponding to the second best predicted SSB (e.g., by sending a PRACH preamble). In one example, the WTRU may follow a procedure considered for failed PRACH transmissions. For example, the WTRU may follow the process of transmitting a PRACH preamble based on the detected beam, waiting for a conventional SSB burst for each transmitted SSB beam, rejecting the current cell and attempting to detect another SSB block or another cell in a different synchro grating, etc.

[0190] In one example, the WTRU can perform a conditional connection. For example, the WTRU can continue the initial access procedure (e.g., via transmission of Msg3) and / or connect to the cell based on a beam with the same spatial relationship as the predicted beam (e.g., with the predicted beam QCL). The WTRU can connect to the cell based on a beam with the same spatial relationship as the first predicted SSB to perform a new initial access procedure. The WTRU can indicate (e.g., to the gNB) that the predicted beam (e.g., it is being used) is not the preferred beam (e.g., via a marker indication). The WTRU can indicate the preferred (e.g., predicted) beam via an indication (e.g., a beam index). The WTRU can indicate the first predicted SSB via a beam index to perform a new initial access procedure. The WTRU can send an indication after connecting to the cell and switching from the initial access procedure to a connectivity mode (e.g., via UCI, MAC-CE, etc.), as part of the initial access signaling (e.g., Msg3) or as part of the indication signaling. After switching to connected mode, the WTRU can send a request to switch to the preferred beam or the first predicted SSB; or the WTRU can receive an instruction to switch to another beam (e.g., from the gNB).

[0191] The accuracy comparison of the prediction can be performed based on at least two RAR messages. In one embodiment, the WTRU can receive more than one RAR message, wherein the WTRU can compare one or more measured parameters for the received RAR message to determine the accuracy of the predicted beam and / or accordingly determine, select, and / or indicate the optimal beam. In one example, a WTRU that has indicated more than one preferred SSB beam (e.g., including detected and / or predicted SSB beams, such as via a set of (combined) PRACH resources, as described herein (see Section 4.4 or Solution #1)) can receive more than one RAR message within the RAR receive window. In one example, the WTRU can receive a first RAR signaling (e.g., RAR PDCCH and / or RAR PDSCH) corresponding to a first detected SSB; the WTRU can receive a second RAR signaling (e.g., RAR PDCCH and / or RAR PDSCH) corresponding to a first predicted SSB, and so on. In one example, the WTRU can determine the corresponding SSB based on the received random access preamble ID (RAPID) detected from the received RAR message.

[0192] The WTRU can measure a first set of one or more beam quality parameters (e.g., the probability of RSRP, RSRQ, SINR, LOS, etc.) based on one or more reference signals (e.g., via RARPDCCH DMRS, RAR PDSCH DMRS, etc.) received in a first RAR signaling (e.g., via a RAR received with the beam of the first detected SSB QCL); the WTRU can measure a second set of one or more beam quality parameters (e.g., the probability of RSRP, RSRQ, SINR, LOS, etc.) based on one or more reference signals (e.g., via RAR PDCCH DMRS, RAR PDSCH DMRS, etc.) received in a second RAR signaling (e.g., via a RAR received with the beam of the first predicted SSB QCL), etc.

[0193] In one embodiment, the WTRU can compare a set of measured parameters (e.g., a first set, a second set, etc.). The WTRU can determine the optimal beam based on the beam with the most favorable beam quality parameters (e.g., RSRP, RSRQ, LOS probability higher than the corresponding threshold and / or theoretical BLER lower than the corresponding threshold, etc.). The WTRU can use the selected optimal beam for further initial access procedures (e.g., Msg3 transmission). In one embodiment (e.g., alternatively), the WTRU can compare the set of measured parameters (e.g., a first set, a second set, etc.) with predicted parameters (e.g., RSRP, RSRQ, LOS probability, etc.) for a predicted beam or predicted parameters for one or more predicted SSBs. To enable the comparison, the WTRU can receive, determine, be provided with, or be (pre)configured (e.g., via MIB, SIB, etc.) one or more parameters or configuration parameters, offset values, scaling rules, and / or scaling values ​​to (re)evaluate and / or scale the set of measured parameters.

[0194] In one example, the WTRU can determine whether the accuracy of the prediction is acceptable, for example, whether the difference between the measured parameter and the predicted parameter is within an acceptable range (e.g., below a corresponding threshold). If the accuracy is acceptable, the WTRU can continue the initial access procedure (e.g., Msg3 transmission), and / or the WTRU can connect to the detected cell. In one example (e.g., otherwise), the WTRU can determine that the difference between one or more of the predicted parameters and the corresponding measured, (re)evaluated, and / or expanded parameters is higher than a corresponding threshold. The WTRU can determine that the accuracy level for the predicted SSB is not within an acceptable range. The WTRU can perform one or more procedures, as described herein, including selecting a second predicted SSB beam, following procedures considered for failed PRACH transmissions, conditional connection, etc.

Claims

1. A wireless transmit / receive unit (WTRU), comprising: Processor and memory, wherein the processor and memory are configured to: Receive an indication of a set of one or more transmitted SSBs included in a Synchronization Signal Block (SSB) burst and an indication of a set of one or more skipped SSBs included in the SSB burst, wherein each of the one or more skipped SSBs is not transmitted by the base station in the SSB burst. Determine and send an indication that the WTRU wants to use the first skipped SSB of the one or more skipped SSBs; The random access preamble is transmitted using one or more random access resources, wherein the random access preamble or one or more of the one or more random access resources indicate the first skipped SSB; and Use the beam associated with the first skipped SSB to receive at least one downlink transmission.

2. The WTRU of claim 1, wherein the processor and memory are configured to: Receive configuration information associated with the one or more transmitted SSBs, wherein the configuration information includes a candidate beam list, wherein the candidate beam list includes beams associated with the first skipped SSB.

3. The WTRU as described in claim 2, wherein the configuration information includes beam index, azimuth, elevation, or aiming angle.

4. The WTRU of claim 1, wherein the random access preamble is transmitted using a beam associated with a first transmitted SSB in a set of one or more transmitted SSBs, and the random access preamble associated with the first transmitted SSB or one or more random access resources indicates the first skipped SSB.

5. The WTRU of claim 1, wherein the one or more random access resources include a first random access resource and a second random access resource, wherein the first random access resource is associated with a first transmitted SSB, and the second random access resource is associated with the first skipped SSB.

6. The WTRU of claim 1, wherein the processor and memory are configured to receive an indication of whether an SSB skip configuration is enabled.

7. The WTRU of claim 1, wherein the processor and memory are configured to: use an artificial intelligence (AI) / machine learning (ML) model to predict a preferred list of SSBs from a set of one or more skipped SSBs.

8. The WTRU of claim 1, wherein the one or more random access resources are based on the one or more transmitted SSBs, the one or more skipped SSBs, or a combination of the one or more transmitted SSBs and the one or more skipped SSBs.

9. The WTRU of claim 1, wherein the first skipped SSB of the one or more skipped SSBs is used for the initial access procedure or after the initial access procedure.

10. The WTRU of claim 1, wherein the indication sent in the random access message 3 using the one or more random access resources indicates the first skipped SSB.

11. A method implemented by a wireless transmit / receive unit (WTRU), the method comprising: Receive an indication of a set of one or more transmitted SSBs included in a Synchronization Signal Block (SSB) burst and an indication of a set of one or more skipped SSBs included in the SSB burst, wherein each of the one or more skipped SSBs is not transmitted by the base station in the SSB burst. Determine and send an indication that the WTRU wants to use the first skipped SSB of the one or more skipped SSBs; The random access preamble is transmitted using one or more random access resources, wherein the random access preamble or one or more of the one or more random access resources indicate the first skipped SSB; and Use the beam associated with the first skipped SSB to receive at least one downlink transmission.

12. The method of claim 11, further comprising: Receive configuration information associated with the one or more transmitted SSBs, wherein the configuration information includes a candidate beam list, wherein the candidate beam list includes beams associated with the first skipped SSB.

13. The method of claim 12, wherein the configuration information includes beam index, azimuth angle, elevation angle, or aiming angle.

14. The method of claim 1, wherein the random access preamble is transmitted using a beam associated with a first transmitted SSB in a set of one or more transmitted SSBs, and the random access preamble associated with the first transmitted SSB or one or more random access resources indicates the first skipped SSB.

15. The method of claim 1, wherein the one or more random access resources include a first random access resource and a second random access resource, wherein the first random access resource is associated with a first transmitted SSB, and the second random access resource is associated with the first skipped SSB.

16. The method of claim 11, further comprising: Receive configuration regarding whether SSB skip is enabled.

17. The method of claim 11, further comprising: Use artificial intelligence (AI) / machine learning (ML) models to predict a preferred list of SSBs from a set of one or more skipped SSBs.

18. The method of claim 11, wherein the one or more random access resources are based on the one or more transmitted SSBs, the one or more skipped SSBs, or a combination of the one or more transmitted SSBs and the one or more skipped SSBs.

19. The method of claim 11, wherein the first skipped SSB of the one or more skipped SSBs is used for the initial access procedure or after the initial access procedure.

20. The method of claim 11, wherein the indication sent in the random access message 3 using the one or more random access resources indicates the first skipped SSB.

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